New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic

A Continuing Medical Education Monograph

Release date: September 30, 2010 Expiration date: September 30, 2013

Editor Contributors Katherine B. Sims, MD Mark J. Alberts, MD, FAHA Louis R. Caplan, MD Massachusetts General Hospital Northwestern University Beth Israel Deaconess Medical Center Harvard Medical School Feinberg School of Medicine Harvard Medical School Boston, Massachusetts Northwestern Memorial Hospital Boston, Massachusetts Chicago, Illinois

This activity is jointly sponsored by the University of Kentucky College of Medicine and CE Health Sciences Inc. New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

A Continuing Medical Education Monograph

Editor Katherine B. Sims, MD Director, Developmental Neurogenetics Clinic Director, Neurogenetics DNA Diagnostic Laboratory Massachusetts General Hospital Associate Professor of Harvard Medical School Boston, Massachusetts

Contributors Mark J. Alberts, MD, FAHA Professor of Neurology Section Chief, Stroke and Northwestern University, Feinberg School of Medicine Director, Stroke Program Northwestern Memorial Hospital Chicago, Illinois

Louis R. Caplan, MD Beth Israel Deaconess Medical Center Professor of Neurology Harvard Medical School Boston, Massachusetts

To receive CME credit for this activity, please review the material in full and complete the online posttest and evaluation form at www.CECentral.com/getcredit (activity code MEN09182). A printable statement of credit will be issued upon successful completion of the required forms.

3 Accreditation This activity has been planned and implemented in accordance with the Essential Areas and Policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the University of Kentucky College of Medicine and CE Health Sciences Inc. The University of Kentucky College of Medicine is accredited by the ACCME to provide continuing medical education for physicians.

The University of Kentucky College of Medicine designates this educational activity for a maximum of 1.5 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

The University of Kentucky College of Medicine presents this activity for educational purposes only. Participants are expected to use their own expertise and judgment while engaged in the practice of medicine. The content of this activity is provided solely by editors who have been selected for their contributions on the basis of recognized expertise in their field. The University of Kentucky is an equal opportunity employer. Release date: September 30, 2010 Expiration date: September 30, 2013

Evaluation and Posttest To obtain CME credit for this activity, please log on to www.CECentral.com/getcredit, enter activity code MEN09182, log in or register for a free account, and complete the online evaluation and posttest. A minimum score of 70% is required on the posttest to receive acknowledgment of completing the activity. A printable statement of credit will be issued upon successful completion of the required forms. This activity should take 1.5 hours to complete.

Overview Conventional risk factors, including age, hypertension, smoking, and obesity, account for 40% to 50% of stroke risk. Routine diagnostic procedures can be used to identify stroke etiology in more than half of patients, but in 20% to 40% of patients, are classified as cryptogenic (ie, unknown cause despite extensive workup). Cryptogenic stroke appears to be more common in young adults than in older individuals. Therefore, other factors, including genetic ones, may be involved in these cryptogenic stroke cases. Because of the unique challenges of diagnosing and managing patients with stroke due to single- gene disorders, there has been a recent increase in published literature on these disorders. Although management of some single-gene disorders, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, is limited to symptomatic management, support, and counseling, other single-gene disorders, including Fabry disease, have treatment options available that may affect the course of the disease. This activity will review the differential diagnosis for cryptogenic stroke and identify the diagnostic and treatment options for managing single-gene disorders associated with ischemic stroke.

Target Audience This activity is designed for neurologists and other health care professionals who have an interest in the diagnosis and treatment of patients with cryptogenic stroke.

Learning Objectives Upon completion of this activity, the participant should be able to • Recognize the incidence of cryptogenic stroke and the need for differential diagnosis • Describe the types of single-gene stroke disorders • Summarize the clinical presentation of genetic stroke disorders • Identify treatment options and prevention techniques for complications resulting from genetic stroke disorders

4 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Faculty Disclosure In accordance with policies set forth by the Accreditation Council for Continuing Medical Education (ACCME), the University of Kentucky College of Medicine Continuing Education Office requires all persons with an opportunity to affect the content of a continuing education (CE) activity to disclose any relevant financial relationship with commercial interests that produce health care goods and/or services consumed by, or used on, patients. Relationships with commercial interests and conflicts of interest resulting from those relationships must be made known to the audience and resolved prior to the activity. Faculty may not accept payment directly from commercial interests for involvement in a CE activity. Pursuant to Standard 2.1 of the ACCME’s Standards for Commercial Support, financial relationships of a spouse/significant other must be disclosed.

Name Company and Relationship Katherine B. Sims, MD Research grant: Genzyme Corporation Mark J. Alberts, MD, FAHA Consultation fees: Genzyme Corporation Louis R. Caplan, MD Advisory board: Avanir Pharmaceuticals; Boehringer Ingelheim; Genentech, Inc.; LifeCycle Pharma A/S; NeuroLogica Corporation; Novovision, Inc.; ReNeuron. Consultant: AstraZeneca Pharmaceuticals; Bayer Schering Pharma; CoAxia, Inc.; Genzyme Corporation; Jones & Davis LLP; Micromedex Solutions; Millennium Pharmaceuticals, Inc.; Novo Nordisk; Takeda Pharmaceutical Company Limited. Speakers list: AstraZeneca Pharmaceuticals; Boehringer Ingelheim; Bristol-Myers Squibb; Otsuka America Pharmaceutical, Inc.; Sanofi-Aventis.

This activity is supported by an unrestricted educational grant provided by Genzyme Corporation.

5 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Introduction

Stroke is a leading cause of death in the United States and a common cause of serious long-term disability.1 Worldwide, strokes occur in approximately 15 million people each year.2 Among these individuals, approximately 5 million die and 5 million are permanently disabled as a result of a stroke.2 Each year in the United States, approximately 795,000 strokes occur; approximately 137,000 people died from stroke in 2006.1 Although most strokes occur in individuals over the age of 65 years, they can happen at any age, and nearly 25% of strokes occur in persons under age 65 years.1 Estimates of the incidence of new cases of stroke in individuals aged 54 years or younger range from 3 to 47 per 100,000 people, varying widely by country.2 In the United States, the incidence of new stroke cases in persons aged 20 to 44 years varies by ethnicity from 10 to 26 per 100,000 people.2 In individuals aged 55 to 84 years, the incidence of stroke is higher in men than in women. However, in those aged 85 years or older, the incidence of stroke is higher in women. In 2006, women accounted for 60.6% of deaths from stroke.3 Women are 3 times more likely to die as a result of stroke than of breast cancer.4 Ischemic strokes, which occur when blood flow to the is blocked, are the most commonly occurring type of stroke and represent approximately 87% of all strokes.5 The determination of stroke etiology is important to help plan treatments that will be effective in preventing another stroke. For most patients who have a stroke, an etiology (eg, atherosclerosis, cardiac embolism, arterial dissection) can be identified; however, the cause of stroke is unknown (ie, cryptogenic) in approximately 20% to 40% of cases.6-8 This figure is highly dependent on the extent of the initial and subsequent evaluations. Some research suggests that cryptogenic stroke is more common in younger patients (ie, those aged 45 years or younger) than in older patients.9,10 Conventional risk factors for stroke include increased age, diabetes mellitus, lack of exercise, dyslipidemia, obesity, hypertension, smoking, drug abuse, and metabolic syndrome.11-15 Such factors account for only approximately half of all stroke risk11-14; other elements, including geographic and genetic factors, are also involved.6,11,16 Genetic factors may contribute to stroke by influencing conventional risk factors for stroke (eg, hypertension, diabetes)13; they may predispose an individual to a specific stroke mechanism (eg, dissection, clotting abnormality) or to a specific subtype of stroke (eg, cardiac, atherosclerotic).12,13 Genetic factors can also influence the size and degree of an infarction, as well as the stroke outcome.12,13

Causes of cryptogenic stroke Some vascular causes of cryptogenic stroke, including occult dissections, very focal atherosclerosis, and central nervous system (CNS) vasculitis, may be missed by noninvasive imaging studies. In such cases, more invasive procedures, such as cerebral angiography or brain biopsy, may be required to make an accurate diagnosis.17,18 Cardiac conditions potentially associated with cryptogenic stroke include patent foramen ovale and atheroma of the aortic arch, detection of which may require transesophageal echocardiography, cardiac magnetic resonance imaging (MRI), or transcranial Doppler ultrasonography.6,19-21 Without thorough examination and laboratory testing, some coagulopathies (eg, Sneddon syndrome, which can be identified with a skin examination for livedo reticularis) can be missed as a potential cause of stroke.21 Other conditions potentially underlying cryptogenic stroke include human immunodeficiency virus/acquired immunodeficiency syndrome infection and drug abuse.22,23 Mitochondrial disorders and other metabolic disorders (eg, homocystinuria, organic acidurias, urea cycle defects) should also be considered.24-26 Additionally, single-gene disorders are important to consider in the differential diagnosis of cryptogenic stroke, particularly in young patients, those who have no or few conventional risk factors for stroke, and/or those who have a family history of stroke.27,28 Appropriate diagnoses of single-gene disorders associated with stroke might be missed because patients may have atypical symptoms or atypical neuroimaging study results. Improved accuracy in diagnosing single-gene disorders associated with cryptogenic stroke will allow for appropriate treatment and better overall patient outcomes. Certain clinical features combined with results from neuroimaging studies in patients with single-gene disorders may produce findings that are suggestive of particular conditions and thereby aid in making an accurate diagnosis.12,29-31 Furthermore, treatment approaches for patients with single-gene disorders may differ from those for patients with conventional stroke, and certain preventive therapies that are commonly used in patients with conventional stroke may be detrimental in patients with single-gene disorders.12

7 The purpose of this monograph is to review the clinical features and diagnosis of several single-gene disorders associated with ischemic stroke, discuss supportive care measures for patients with disorders that currently have no available ameliorative or curative treatments, and help clinicians create appropriate treatment regimens for those conditions with currently available treatments. Additionally, case studies describing patients with some of these conditions are included in order to increase the reader’s familiarity with single-gene disorders associated with stroke. The single-gene disorders to be reviewed in this monograph are cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL); cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL); retinal vasculopathy with cerebral (RVCL); (MMD); Fabry disease (FD); sickle cell disease (SCD); Marfan syndrome; neurofibromatosis type 1 (NF1); and mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke- like episodes (MELAS) (Table 1). Many of these disorders have ocular and/or skin manifestations associated with them, as shown in Table 2. Mutations in the COL4A1 gene and inherited disorders of blood coagulation, which may predispose individuals to stroke, will also be discussed.

Table 1. Summary of Single-Gene Disorders Associated With Ischemic Stroke

Mode of Gene Disorder Inheritance (OMIM #) Stroke Mechanism(s) Clinical Features Diagnostic Test(s) CADASIL AD33 Notch333 Small-vessel disease13,27 with , psychiatric Genetic screening, skin (125310)32 disturbances, cognitive decline, biopsy12,13,27 seizures, retinal irregularities12,13,27 CARASIL AR12 HTRA1 56 Small-vessel disease12 Alopecia, psychiatric disturbances, Genetic screening12,56 (600142)55 acute back pain, progressive mental and motor deterioration12,61,62 RVCL AD67 TREX1 67 Small-vessel disease70 Migraine, psychiatric disturbances, Genetic screening12 (192315)66 retinal irregularities, renal dysfunction12 MMD AD with Unknown Large-vessel disease12 Seizures, headache, movement Imaging studies86

as a principal manifestation incomplete (252350, disorders, sensory impairment, Disorders with ischemic stroke penetrance 608796, dizziness, cognitive decline12,83 (suggested)80 607151)74,78,79 FD X-linked12,13 GLA13,91 Large- and small-vessel Angiokeratoma, neuropathic Genetic screening, (301500)90 disease13,100 pain, renal failure, cardiac failure, measurement of hypohidrosis, cataracts, corneal a-galactosidase opacities, gastrointestinal dysmotility, activity, imaging acroparesthesia13 studies12,13,27,173 SCD AR13 HBB 13 Large- and small-vessel Pain crises, vaso-occlusive crises, Peripheral blood (603903)118 disease, hemodynamic pulmonary and abdominal crises, smear, genetic insufficiency12,13,100 bacterial infection, anemia, pulmonary mutational analysis, hypertension, joint necrosis13,120 hemoglobin electrophoresis13,120

Disorders with stroke 27,139

as a recognized feature MELAS Maternal MT-TL1 Complex, with neuronal Migraine (sometimes complex), Mutational analysis of (mitochondrial)27 (540000)138 and microvascular seizures, weakness, developmental mitochondrial DNA in components13 delay, cognitive decline, hearing blood or other tissue13 loss13,140 Marfan AD27 FBNI 127 Large-vessel disease27 Tall stature, arm span > height, Clinical features, syndrome (154700)126 ectopia lentis, scoliosis, mitral valve genetic screening13,27 prolapse, aortic root dilatation, aortic dissection12,128

NF1 AD12 NF1 27 Large- and small-vessel Neurofibromas, café-au-lait lesions, Clinical features27 (162200)132 disease136 skeletal anomalies, iris hamartomas, hypertension, gliomas, optic nerve tumors12,135 associated with stroke Disorders occasionally

Abbreviations: OMIM, Online Mendelian Inheritance in Man; CADASIL, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; AD, autosomal dominant; CARASIL, cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy; AR, autosomal recessive; RVCL, retinal vasculopathy with cerebral leukodystrophy; MMD, moyamoya disease; FD, Fabry disease; SCD, sickle cell disease; MELAS, mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes; NF1, neurofibromatosis type 1.

8 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Table 2. Major Ocular and Skin Manifestations of Single-Gene Disorders Associated With Stroke

Disorder Major Ocular Manifestations Major Skin Manifestations CADASIL Poorly characterized; may have arteriole sheathing or None narrowing and/or arteriovenous nicking12

CARASIL None None RVCL Retinopathy with progressive visual loss12,72 None MMD None None FD Corneal opacities (commonly cornea verticillata)103,107 Angiokeratoma103 SCD Retinopathy, retinal infarcts, retinal detachment120 Leg ulcers120 Marfan syndrome Ectopia lentis128 Stretch marks (in the absence of significant weight changes) on the shoulders, mid-back, and thighs128

NF1 Iris hamartomas (Lisch nodules)12,134,135 Café-au-lait lesions, axillary freckling12,134,135 MELAS Visual impairment,141 pigmentary retinopathy140 Cutaneous purpura, hirsutism, scaly pruritic rash140 Abbreviations: CADASIL, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; CARASIL, cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy; RVCL, retinal vasculopathy with cerebral leukodystrophy; MMD, moyamoya disease; FD, Fabry disease; SCD, sickle cell disease; NF1, neurofibromatosis type 1; MELAS, mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Genetics Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (Online Mendelian Inheritance in Man [OMIM] #12531032) is an autosomal dominant disorder caused by mutations in the Notch3 gene on 19p13.1-13.2,32,33 which is expressed on vascular smooth muscle cells.34 Most patients with CADASIL have affected family members, but the disorder can also be found in individuals who have no family history.27,35 A relationship between individual mutations and phenotype has not yet been elucidated.12

Pathology and pathophysiology The disorder is characterized by nonatherosclerotic, nonamyloid vasculopathy that mainly affects the small vessels of the brain.12,27 The vasculature outside of the brain (eg, muscle, skin, peripheral nerves, liver, heart, viscera) may be affected without causing symptoms.12 Mutations in Notch3 lead to the production of mutant Notch3 receptors that accumulate next to granular osmiophilic material (GOM) at the cytoplasmic membrane of vascular smooth muscle cells and in capillaries.34 Brain pathology in patients with CADASIL is characterized by small, deep infarcts in the and , along with regions of demyelination and white matter gliosis.12,27,36

Clinical presentation The mean age of CADASIL onset is approximately 45 years.12,36 The disorder typically leads to death 10 to 25 years after onset, with death usually occurring between 60 and 65 years of age.36 Transient ischemic attacks (TIAs) and ischemic stroke are major features of CADASIL. They are the first symptoms in approximately 70% of these patients, and they may affect approximately 84% of patients with CADASIL sometime during the course of their illness.36,37 In patients with CADASIL, TIAs and strokes tend to be lacunar and subcortical, affecting the white matter or basal ganglia.36 Subcortical strokes usually occur in the absence of typical risk factors for stroke.36 The brain stem is affected in approximately 45% of cases.38 Strokes typically manifest in these patients with hemiparetic or hemisensory symptoms, with or without resulting permanent deficits.12 Approximately 80% of patients with CADASIL who have had a stroke have further strokes that lead to progressive disability and a pseudobulbar state (ie, bilateral hemisphere dysfunction that may cause difficulties with chewing and swallowing) in 31% to 52% of patients.12,36

9 Migraine occurs in approximately 20% to 40% of patients with CADASIL and is the first presenting symptom in approximately one-third of patients.36,39 are less likely to occur in patients who have stroke as their first symptom of CADASIL than in other patients.12 Migraine with aura is more common than is migraine without aura,40 and the aura is often atypical and prolonged in patients with CADASIL.39 Because hemiplegic or hemisensory disturbances may be associated with migraine in patients with CADASIL, it may be difficult to distinguish between TIAs or lacunar strokes and migraine.12,39 Migraines may increase in frequency or severity before an ischemic event but often cease or decrease in frequency after a stroke.12,36,40 Patients with CADASIL, particularly those who have had a TIA or stroke, often develop cognitive decline between the ages of approximately 40 to 59 years.12 This decline is slowly progressive, with subtle impairments in higher mental function (eg, concentration, organization, planning) typically occurring first.12,36 Later, memory may be affected, which may lead to subcortical dementia.12,36 Additionally, disturbances in memory, concentration, and attention may be precipitated by clinically overt strokes.12 Dementia may affect 30% to 90% of patients with CADASIL, depending on the age at observation.36 Dementia at the onset of CADASIL is relatively uncommon, presenting in only 3% to 4% of patients.36 Mood disorders are the most commonly reported psychiatric findings in patients with CADASIL, affecting approximately 20% of patients.12,36 Of these, depression is common and may be the initial manifestation of CADASIL.12,36 Depression may also develop secondary to the physical or mental disabilities associated with CADASIL.12 Other psychiatric conditions that have been reported in patients with CADASIL include aggression, agitation, delusional states, dysthymia, emotional lability, mania, paranoia, and schizophrenia-like symptoms.12 Seizures occur in 5% to 10% of patients with CADASIL and may be partial or generalized.12,36 They may occur as a primary manifestation of CADASIL or be secondary to ischemic damage of cerebral tissue.12,36 Ocular symptoms in patients with CADASIL are poorly characterized but may include arteriolar narrowing and sheathing and arteriovenous nicking.12 Retinal hemorrhages can occur.41

Diagnosis A diagnosis of CADASIL should be considered in young patients with symptoms of subcortical cerebrovascular disease but without classical risk factors for stroke.27 Magnetic resonance imaging is a useful tool in the evaluation of patients suspected of having CADASIL. (Figure 1)42 Carriers of a Notch3 mutation who are aged 35 years or older have abnormal MRIs, with confluent, symmetric noted in both cerebral hemispheres, particularly in the periventricular regions.12 The periventricular region and centrum semiovale may show punctuate or diffuse high signal abnormalities.12 Lacunar infarctions are common in the temporal lobes and periventricular region; the frequency of these infarcts increases with the age of the patient.12 Hyperintensities at the poles of the temporal lobes are highly characteristic of patients with CADASIL, and hyperintensities involving the external capsule area and corpus callosum are less specific markers for CADASIL.43 Focal microhemorrhages also are common.44,45 Routine neuroimaging results have poor correlation with a patient’s clinical state, but quantitative measurements, such as total lesion volume and weighted MRI, may correlate with disability and cognitive decline.12 Genetic analysis for Notch3 mutation is considered the definitive diagnostic method for CADASIL.12 Most laboratories initially screen exon 4, where mutations are most common, but may later screen other exons, depending on the prevalence of mutations in the particular geographical area. Muscle or skin biopsy with electron microscopy to detect GOM is a faster alternative to genetic testing for diagnosis of CADASIL.46-48 This approach has 100% specificity, but its reported sensitivity varies widely, from 45% to 100%.46-48 Immunostaining of biopsied tissue with monoclonal for Notch3 may also be used.12 Although this approach is highly sensitive and specific, false positives and negatives can occur, so immunostaining is usually considered to be an adjunct to diagnosis through genetic testing.12 The differential diagnosis for CADASIL includes CARASIL, multiple sclerosis, Binswanger disease, primary angiitis of the nervous system, familial hemiplegic migraine, MELAS, and Alzheimer disease.12,49-54

10 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Figure 1. Axial FLAIR (A, B, and C) and T2-weighted (D) MRI brain scans from patients with CADASIL. The images in A and B are from asymptomatic patients with depression. Note temporal lobe lesions even in asymptomatic patient (B). A and D show periventricular diffuse white matter ischemic lesions and multiple lacunar lesions in the thalamus, , and basal ganglia.42 Figure courtesy of Bohlega S, Al Shubili A, Edris A, Alreshaid A, Alkhairallah T, AlSous MS, Farah S, and Abu-Amero KK. Abbreviations: FLAIR, fluid-attenuated inversion recovery; MRI, magnetic resonance imaging; CADASIL, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

11 Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL)

Genetics As its name implies, CARASIL (OMIM #60014255), also known as Maeda syndrome, is an autosomal recessive disorder that is associated with mutations in the HTRA1 gene on chromosome 10q.12,55,56 HTRA1 codes for a serine protease that inhibits signaling in members of the transforming growth factor-b (TGF-b) family.

Pathology and pathophysiology Increased signaling of TGF-b leads to increased synthesis of extracellular matrix proteins and, thereby, vascular fibrosis.56-58 The pathology of CARASIL is characterized by chronic ischemia affecting the small blood vessels of the , with diffuse and homogeneous lesions in the white matter.56,59 Unlike with CADASIL, no accumulation of GOM is associated with CARASIL.60

Clinical presentation To date, CARASIL has been reported only in persons of Japanese or Chinese origin.59,60 Onset typically occurs in young adulthood (age range, 25-30 years), and the average clinical course of the disorder is reported to be 7.6 years.61,62 Features commonly noted in patients with CARASIL include TIAs and pyramidal, extrapyramidal, and pseudobulbar symptoms.61 Stroke occurs in approximately two-thirds of individuals with CARASIL63; other common symptoms include alopecia, acute back pain, intervertebral disc disease, spinal deformity, progressive mental and motor deterioration, dementia, and psychiatric disturbances such as emotional lability and euphoria.60-64 Neurologic symptoms are often preceded by non-CNS symptoms.60 Hypertension and migraine have not been reported in association with CARASIL.60,62

Diagnosis The most important consideration in the differential diagnosis for CARASIL is CADASIL. Although the 2 conditions share many features, differences exist. First, CADASIL has an autosomal dominant pattern of inheritance, whereas CARASIL has an autosomal recessive pattern.12 Migraine is associated with CADASIL, but not with CARASIL.39,60 On MRI, lesions of the white matter are homogeneous and diffuse in CARASIL, but are punctuated and nodular in CADASIL.59,65 Although psychiatric disturbances may be associated with both disorders, depression is common in patients with CADASIL, whereas euphoria and emotional lability have a greater prevalence in CARASIL.36,63 Finally, a negative screening for Notch3 mutations is suggestive of CARASIL.12 Because CARASIL has recently been found to be associated with mutations in the HTRA1 gene,56 genetic screening for such mutations may become a preferred diagnostic approach. In the meantime, confirmation of vascular degeneration in the absence of GOM on autopsy may provide a definitive diagnosis of CARASIL.61

Retinal vasculopathy with cerebral leukodystrophy (RVCL)

Genetics Retinal vasculopathy with cerebral leukodystrophy (OMIM #19231566) is a new term that encompasses 3 previously described diseases with a common etiology: cerebroretinal vasculopathy (CRV); hereditary vascular retinopathy (HVR); and hereditary endotheliopathy with retinopathy, nephropathy, and stroke (HERNS). These disorders are now considered phenotypic variants of the same genetic abnormality (ie, RVCL).67 This autosomal dominant disorder is caused by mutations of TREX1, a gene that encodes a 3′-5′ DNA exonuclease that has been suggested to have roles in DNA editing, granzyme A–mediated cell death, and cell homeostasis.66,68

Pathology and pathophysiology The phenotype noted in RVCL appears to be caused by the loss of the carboxyl terminus on the TREX1 enzyme.68 Although enzyme function does not seem to be affected, its localization is changed: mutant TREX1 disseminates freely throughout the cell rather than localizing to a perinuclear site.68 It is currently believed that, as a result, DNA intermediates accumulate within cells and trigger abnormal immune responses.69

12 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

The disorder is characterized by generalized vasculopathy that predominantly affects the brain, retina, and kidneys. Capillary and arteriole integrity are disrupted, and fibrinoid necrosis of vessel walls is seen.68,70 Systemic basement membrane abnormalities, including multilaminated basement membranes in the skin, kidney, and stomach, are also noted.70 Breakdown of the blood-brain barrier occurs, and space-occupying lesions are noted in the frontoparietal region of the brain.70

Clinical presentation Onset of RVCL ranges from young adulthood to middle age, and death typically occurs within approximately 10 years from the time of onset.67,68,71 The disorder is characterized by progressive visual loss, usually beginning in the third or fourth decade of life. This visual loss is secondary to a retinopathy that develops when vascular occlusions result in large ischemic areas.67,70-73 Microaneurysms and telangiectatic capillaries may also be noted around the macula (Figure 2).72 The retinopathy of RVCL may be difficult to distinguish from hypertensive or diabetic retinopathy, and this can delay diagnosis of RVCL, particularly in the absence of other symptoms. Other common features of RVCL are stroke, dementia, migraine or migraine-like headaches, nephropathy, and psychiatric disturbances.67,70,71 Some patients with RVCL also have Raynaud phenomenon, a condition characterized by a pathological vasomotor reaction to cold exposure.71,72 Patients with RVCL can develop pseudotumors formed by the coalescence of small infarcts in cerebral white matter.67,71-73 These lesions usually present in patients ≤50 years of age and are a significant cause of morbidity.71,72

Figure 2. Fluorescein angiogram of the right eye of a 45-year-old man with stage 2 hereditary vascular retinopathy showing microaneurysms, telangiectatic capillaries, and avascular areas, especially located superior to the macula and nasally to the optic disc. Figure from Terwindt GM, Haan J, Ophoff RA, et al. Clinical and genetic analysis of a large Dutch family with autosomal dominant vascular retinopathy, migraine and Raynaud’s phenomenon. Brain. 1998;121(pt 2):303-31672 by permission of Oxford University Press.

13 Diagnosis Genetic screening for RVCL will be negative for mutations in Notch3 and HTRA1 and positive for mutations in TREX1.12,67 The differential diagnosis of RVCL includes familial exudative vitreoretinopathy; other hereditary disease with vascular retinopathies (eg, facioscapulohumeral dystrophy, autosomal dominant peripheral retinal neovasculation, autosomal dominant cystoid macular edema, hereditary central retinal angiopathy, focal parafoveal retinal telangiectasia, inherited retinal venous beading, autosomal dominant retinal arteriolar tortuosity); systemic lupus erythematosus and other systemic collagen vascular diseases and vasculitic syndromes; amyloid angiopathy; and CADASIL.72,73

Moyamoya disease (MMD)

Genetics Moyamoya disease (OMIM #25235074) is a disorder of unknown etiology for which no pathogenic gene has been identified.12,75 Results from genetic studies have suggested linkage to at least 5 different chromosomal regions: 3p24.2-p26,74,76 6q25,75,77 8q23,77-79 12p12,77 and 17q25.80,81 To date, the evidence for a pathogenic gene for familial MMD on chromosome 17q25 is most compelling, as results from 2 separate linkage analyses have identified it as a candidate locus.80,81 Additionally, Mineharu et al80 suggested that the mode of inheritance for MMD is autosomal dominant with incomplete penetrance. Moyamoya-like phenomena have also been associated with a number of genetic conditions, including SCD, , NF1, and Down syndrome; such cases are referred to as moyamoya syndrome.12,82

Pathology and pathophysiology Moyamoya disease is characterized by progressive bilateral stenosis and eventual occlusion of the terminal portions of the internal carotid arteries.12,83 Stenosis/occlusion may also be found in the posterior, middle, and anterior cerebral arteries emanating from the circle of Willis.83 Cases of unilateral stenosis/occlusion (which may eventually become bilateral) are referred to as probable MMD.82 Stenosis and occlusion of vessels lead to reduced blood flow and compensatory formation of new vessels around the circle of Willis.12,83 On imaging, this new vasculature resembles a puff of smoke; moyamoya is Japanese for puff of smoke (Figure 3).

Clinical presentation Most often, MMD presents in the first decade of life, but it may also present in adulthood (commonly during the third or fourth decade of life).83 Ischemic symptoms, which are secondary to vascular stenosis, commonly present during childhood.12,83 Such symptoms are often precipitated by hyperventilation84 and may consist of hemiparetic stroke, seizures, headache, sensory impairment, dizziness, and movement disorders, including a fluctuating, transient disorder that resembles chorea.12,83,85 Headache in patients with MMD may be migraine-like and is often refractory to medical treatment.86 Additionally, 50% to 60% of patients with MMD have a gradual deterioration of cognitive function, possibly attributable to recurrent strokes.83 Ischemic stroke and TIAs both have prevalence rates estimated to range from 50% to 75% in patients with MMD.86 Symptoms of MMD in adults are similar to those seen in children, but cerebral hemorrhage is more common in adults (prevalence range, 10%-40%).12,83,86 These hemorrhages can be intraventricular, intraparenchymal, or subarachnoid, and they often involve the basal ganglia and thalamus.86,87 They often develop from the rupture of fragile blood vessels that have formed to improve blood supply around areas of stenosis/occlusion.12 Hemorrhages may also develop as a result of circulatory pattern changes at the base of the brain that cause increased shear stress on the vessels in this area.86 Hemorrhage is a common cause of death in MMD; overall mortality rates of MMD range from 4.3% in children to approximately 10% in adults.83

14 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Figure 3. Right internal carotid artery digital subtraction angiography in a patient with moyamoya disease. Image courtesy of Dr. Frank Gaillard.

Diagnosis Table 3 shows diagnostic criteria for MMD.84,88 An additional instructive pathological finding is the stenosis/occlusion of the lumen as a result of intimal thickening around the terminal portion of the internal carotid artery.84,88 These lesions are typically bilateral, and lipid deposits may be noted in the proliferating intima. Stenosis or occlusion of the arteries that constitute the circle of Willis is present to varying degrees and is associated with fibrocellular intimal thickening, waving of the internal elastic lamina, and thinning of the media.84,88 Small vascular channels (eg, anastomotic branches, perforators) may be prevalent around the circle of Willis, and a netlike conglomerate of small vessels may be present in the pia mater.84,88 The differential diagnosis of MMD is very wide and includes neurofibromatosis type 1 or 2, pituitary tumors, Tolosa-Hunt syndrome, primary CNS vasculitis, infections or lymphoproliferative disorders, benign angiopathy of the CNS, metabolic diseases (eg, methylmalonic or propionic acidemia, FD, homocystinuria/homocysteinemia, MELAS, hyperglycemia/ hypoglycemia), hypercoagulable states (eg, polycythemia vera, thrombotic thrombocytic purpura, idiopathic thrombocytosis, sickle cell anemia, inherited or acquired clotting abnormalities), drug abuse, and medication side effects.82,83,89 However, a diagnosis of MMD can be easily confirmed by analysis of the results of one or more of the imaging studies listed in Table 3.86

15 Table 3. Diagnostic Criteria for MMD84,88

A. At least the following findings on cerebral angiography i. Occlusion or stenosis at the terminal part of the internal carotid artery and/or at the proximal part of the middle and/or anterior cerebral arteries ii. Vascular networks in the vicinity of the occlusive/stenotic lesions in the arterial phase are abnormal iii. i and ii are present bilaterally

B. All of the following findings i. MRA showing stenosis/occlusion at the terminal part of the internal carotid artery and at the proximal part of the middle and anterior cerebral arteries

ii. MRA showing abnormal vascular networking in the basal ganglia or MRI showing >2 apparent flow voids on one side of the basal ganglia iii. i and ii are present bilaterally

C. Elimination of the following conditions: arteriosclerosis, autoimmune disease, brain neoplasm, Down syndrome, head trauma disease, irradiation to the head, meningitis, neurofibromatosis type 1 (von Recklinghausen disease), and other conditions (eg, SCD, tuberous sclerosis)

Definite case (adult): fulfills C and either A or B. Definite case (child): fulfills C and A.i and A.ii (or B.i and B.ii) unilaterally, plus marked stenosis of the terminal portion of the internal carotid artery on the opposite side. Probable case (adult or child): fulfills C and A.i and A.ii (or B.i and B.ii) unilaterally. Abbreviations: MMD, moyamoya disease; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; SCD, sickle cell disease.

Fabry disease (FD)

Genetics Fabry disease (OMIM #30150090), also known as Anderson-Fabry disease, is an X-linked disorder that is caused by deficiency in a-galactosidase A and is associated with mutation of the GLA gene located on Xq22.12,27,90,91

Pathology and pathophysiology Deficiency ina -galactosidase leads to the accumulation of glycosphingolipids, particularly globotriaosylceramide, in vascular endothelial cells throughout the body, including the CNS; affected cells can be found in ocular vasculature; renal tubule cells, podocytes, and glomeruli; cardiac muscle and conducting fibers; autonomic ganglia; cortical and structures; and skin.13,27,92,93 Glycosphingolipid accumulation is presumed to lead to cellular dysfunction and, in turn, organ dysfunction.94 Polymorphisms in the genes that code for interleukin-6, endothelial nitric oxide (NO) synthase, factor V, and protein Z may also affect some aspects of FD, as proteins coded for by these genes are associated with vascular wall biology, clotting mechanisms, and inflammation, all of which may affect the extent of small-vessel disease in patients with FD.95 Fabry disease may be classical or atypical in its presentation, and this variability is particularly true in women, as they are mosaic for the expression of cellular and organ pathology. Male patients with classical FD typically have a-galactosidase A activity that is <1% of normal and have a wide spectrum of symptoms; however, some male patients with atypical FD have some residual a-galactosidase A activity, and their symptoms are often limited to one or a few organs.96-98 Enzyme activity in females with FD is typically 25% to 75% of normal levels99 but can be normal in some cases. Despite a-galactosidase A activity levels that are not severely deficient (as in men), most women with FD have some clinical symptoms and are at risk for early stroke.100 Some women may be as severely affected as male patients with FD.101 The vascular mechanisms underlying the pathophysiology of FD are not well understood. Older theories postulated that an obstructive vasculopathy caused by glycosphingolipid accumulation led to ischemic lesions.102 However, more recent findings suggest that the FD vasculopathy results from a complex interaction of the following factors: (1) abnormalities in blood components, such as procoagulants and anticoagulants; (2) blood flow abnormalities (eg, cerebral hyperperfusion); (3) vessel wall abnormalities (eg, dolichoectasia, disturbed vasoreactivity, disturbed autoregulation); and (4) a prothrombotic state with increased release of oxygen reactive species.102,103

16 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Clinical presentation Because FD is an X-linked disorder, men are typically affected more severely than are heterozygous women.27,101 However, serious and severe manifestations of FD have been increasingly recognized in women.104 Onset of FD symptoms typically occurs in childhood or adolescence and tends to be earlier in boys than in girls and women.13,94 The median cumulative survival in men with FD is 50 years, which is 20 years less than that of the general population.92 Women with FD have a life expectancy approximately 15 years shorter than that of the general population.92,104 Multiple causes of death, such as renal or cardiac failure and stroke, are often cited for patients with FD.92 Compared to the general population, patients with FD have an approximately 20-fold greater risk of ischemic stroke or TIA.103 Both large and small strokes may occur, and these strokes typically present during the third decade of life.27,100,103 Dolichoectasia of intracranial arteries, commonly involving the basilar and carotid arteries, may lead to flow stagnation and eddy formation and is a common feature underlying ischemic events in patients with FD.102,105 Other features of FD, including autonomic dysfunction with orthostatic hypotension or peripheral vasomotor instability,105,106 may add to the risk of ischemic stroke. Neuropathic pain is a hallmark of FD that typically presents before the age of 20 years. Patients develop burning pain in the hands and feet, which tends to be most severe between the ages of 20 and 40 years.92,94,103 Other clinical features of FD that may aid in the clinical recognition and diagnosis of this disorder include angiokeratoma (Figure 4) and hypohidrosis, both of which are common in childhood or adolescence.13,92,94 Corneal opacities (seen only by slit-lamp examination), the most common type of which is cornea verticillata, are prevalent in late adolescence.103,107 Complications that involve the brain, heart, or kidneys often follow in mid-adulthood. Progressive proteinuria and gradual decline in glomerular filtration rate over time lead to end-stage renal failure; as a result, patients often require dialysis and/or kidney transplantation.108,109 Cardiac complications of FD may include progressive hypertrophic cardiomyopathy, conduction defects, arrhythmias, atrial fibrillation, valvular disease, progressive bradycardia, and coronary artery stenosis.103 Cardiomyopathy may be a predominant finding, especially in heterozygotes.97,98,110 Gastrointestinal tract symptoms (eg, postprandial bloating with nausea, vomiting, or explosive diarrhea), episodic and progressive tinnitus and hearing loss, and reduced quality of life are common.92,111 Dysmorphic facial features (representing soft-tissue glycosphingolipid storage) may also be present in patients with FD.92,112

Diagnosis Fabry disease should be suspected in children who have unexplained acute or chronic pain episodes in the limbs, particularly after exercise or with fever/illness; unexplained gastrointestinal tract disturbances; angiokeratomas; hypohidrosis; and/or corneal lesions. In adults, FD should be suspected in those who have strokes of unclear cause or who develop unexplained renal dysfunction/failure or cardiomyopathy.94 Imaging studies are useful in the diagnosis of FD (reviewed by Schiffmann103). Magnetic resonance imaging findings in patients with FD and stroke are similar to those of patients with ischemic stroke. However, approximately 13% of strokes in patients with FD are hemorrhagic.100 White matter abnormalities may also be seen in patients with FD and no history of TIA or stroke. In addition, T1-weighted MRI often shows symmetric lesions in the posterior thalamus and pulvinar, and MRI or computed tomography (CT) may show dystrophic calcifications in gray-white matter junction areas, basal ganglia, and the .103,113,114 Pulvinar infarcts are especially important diagnostically, since they are often found in patients with FD but are rare in other patient groups.114 Abdominal ultrasound, CT, or MRI may show renal parapelvic cysts.103 Additionally, MRI or magnetic resonance angiography (MRA) may be used to identify areas of arterial dolichoectasia.29,102,105 Assessment of a-galactosidase A levels/activity in white blood cells, dried blood spots, or cultured skin fibroblasts is diagnostic in males; however, diagnosis via this method is not reliable in women becausea -galactosidase A levels can fall within normal ranges in heterozygous women with this X-linked disease.12,13,115 Therefore, genetic screening for GLA gene mutations is required for confirmation of an FD diagnosis in women.103 Because of the variability in presenting symptoms and organ systems affected, the differential diagnosis of FD can be broad. Possibilities to consider may include disorders that involve the CNS (eg, multiple sclerosis, CADASIL), hearing loss, retinal vascular abnormalities (eg, diabetes), gastrointestinal dysmotility (eg, irritable bowel syndrome), cardiomyopathy (eg, MELAS), proteinuria, the peripheral nervous system (eg, diabetic and other small-fiber neuropathies), and/or the skin.116,117

17 Figure 4. Example of an angiokeratoma. Angiokeratomas are vascular lesions that are characterized by thin-walled vessels beneath a hyperkeratotic epidermis. In Fabry disease, they are usually periumbilical or in the bathing suit region but can also be seen on the thorax, lips, gums, or other regions of the body. Angiokeratomas are asymptomatic and are often referred to as angiokeratoma corporis diffusum (image courtesy K. Sims).

18 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Sickle cell disease (SCD)

Genetics Sickle cell disease (OMIM #603903118) is an autosomal recessive disorder that can result from either a homozygous state for hemoglobin S (HbS) or a compound heterozygous state with HbS and another hemoglobinopathy, such as hemoglobin C or b thalassemia.12,13,118,119

Pathology and pathophysiology Compared with normal hemoglobin A, HbS is less soluble and tends to polymerize under deoxygenation conditions, which leads to the formation of the sickle-shaped erythrocytes that are characteristic of SCD.119,120 Sickled cells interact with other blood cells and the endothelium in the vasculature to cause vaso-occlusion.121 The cells repeatedly adhere to the endothelium and are forcibly removed by high shear forces, resulting in endothelial injury, intimal proliferation, and narrowing of the lumen.122 Some sickled erythrocytes also hemolyze intravascularly and release hemoglobin into the plasma.121 Increased plasma hemoglobin levels lead to dysregulation of NO homeostasis; reduced endothelial NO bioavailability ultimately results in a skewed vasodilatation/vasoconstriction balance (toward vasoconstriction), which increases the likelihood of sickle vaso-occlusion.121 The severity of SCD varies by subtype.120 The HbSS (homozygous for HbS) subtype generally results in moderate to severe disease and is associated with the shortest duration of survival, and the HbS/b0 thalassemia (heterozygous) subtype is clinically indistinguishable from the HbSS subtype. The HbS/b+ thalassemia and HbSC (heterozygous) subtypes tend to result in mild or moderate disease severity. In patients with severe SCD, vaso-occlusive complications may lead to death at a very young age, whereas mild SCD may go undetected until adulthood.120

Clinical presentation Pain, the most common symptom in the presentation of vaso-occlusive crisis in patients with SCD, may involve the abdomen, bones, joints, and soft tissue.120 Patients with the vaso-occlusive subphenotype of SCD may also have acute chest syndrome (ie, fever or respiratory symptoms associated with a new infiltrate on chest imaging), joint necrosis, stroke, acute splenic sequestration, hepatic sequestration, or renal disease.120 Common manifestations of the hemolytic subphenotype of SCD include chronic anemia, gallstones, pulmonary hypertension, priapism, leg ulceration, sudden death, and possibly stroke.120 Sickle cell disease is the most common cause of stroke in children.123 Stroke affects approximately 30% of children with SCD, and 11% of SCD patients have had a stroke by the age of 20 years.120 Ischemic stroke is more common in children with SCD, but hemorrhagic stroke is more common in adults with SCD.13 Strokes that are associated with large-vessel disease tend to be more clinically overt, whereas strokes associated with small-vessel disease are more likely to result in small “silent” infarcts.13

Diagnosis In patients suspected of having SCD, a peripheral blood smear can be performed to identify sickle-shaped erythrocytes, and hemoglobin electrophoresis may be used to differentiate homozygous and heterozygous individuals.13,120 Mutational analysis provides a definitive diagnosis, which may be important for couples who are at risk of having an affected child.124 Additionally, transcranial Doppler ultrasonography measurements of blood flow velocity in large intracranial arteries is helpful in the identification of patients who are at high risk for .125 The differential diagnosis for SCD includes numerous disorders such as acute coronary syndrome, acute or chronic anemia, gout and pseudogout, hepatitis, osteomyelitis, pancreatitis, pelvic inflammatory disease, and rheumatic fever.120

19 Marfan syndrome

Genetics Marfan syndrome (OMIM #154700126) is an autosomal dominant connective tissue disorder caused by mutations in the FBN1 gene, which encodes fibrillin.126-128 Approximately three-quarters of patients with Marfan syndrome have an affected parent; the remainder of cases represent new gene mutations.128 More than 500 mutations in the FBN1 gene have been identified, and genotype-phenotype correlations are tentative.127 Additionally, evidence suggests that abnormalities in the TGF-b signaling pathway may lead to the development of a Marfan-like phenotype, and mutations in the TGFBR1 and/or TGFBR2 genes may lead to related disorders, including Marfan syndrome type II or Loeys-Dietz aortic syndrome.127,128

Pathology and pathophysiology Mutations in the FBN1 gene lead to the production of abnormal fibrillin, a major component of microfibrils. Because microfibrils are structural components of many connective tissues, fibrillin abnormalities can weaken several tissues: the aortic wall, ligaments, lung airways, spinal dura, and lens zonules.128

Clinical presentation Cardinal features of Marfan syndrome include tall stature, an arm span that is greater than the patient’s height, ectopia lentis (dislocation of the lens of the eye), scoliosis, mitral valve prolapse, aortic root dilatation, and aortic dissection.12,128 Neurovascular complications have been estimated to occur in approximately 3.5% of patients with Marfan syndrome and primarily consist of cardioembolic stroke.129 Increased age, valvular heart disease, atrial fibrillation, prosthetic heart valves, and chronic anticoagulant therapy may increase a patient’s risk of neurovascular complications.129

Diagnosis Diagnosis of Marfan syndrome is based mainly on clinical criteria and should be considered in young patients who have had a stroke of cardioembolic origin or who have aortic dissection/dilatation. Other criteria with high diagnostic specificity include skeletal manifestations (eg, tall stature, arm span > height), ocular abnormalities (eg, ectopia lentis), and positive family history.27,128 De Paepe et al130 describe the diagnostic criteria for Marfan syndrome in greater detail. Because mutations in the FBN1 gene are numerous and spread throughout the gene,127 genetic testing for Marfan syndrome may involve screening of the entire gene, which is costly and time consuming.128 Targeted mutational analysis can also be performed but offers little prognostic value.128,131 The differential diagnosis for Marfan syndrome mainly includes Ehlers-Danlos syndrome, fragile X syndrome, gigantism, acromegaly, hyperpituitarism, hyperthyroidism, and Klinefelter syndrome.128

Neurofibromatosis type 1 (NF1)

Genetics Neurofibromatosis type 1 (OMIM #162200132), also known as von Recklinghausen disease, is an autosomal dominant multisystem disorder of mesodermal and epidermal tissue.12,132,133 The disorder is caused by mutations in the NF1 gene, which encodes the tumor-suppressing protein neurofibromin.133 The disorder displays complete penetrance but variable expression.134 More than 250 mutations in the NF1 gene have been identified, most of which result in the production of truncated neurofibromin.133,135 An especially severe phenotype has been noted in patients who have deletion of the entire NF1 gene, but it is unclear whether the severity of this phenotype is a function of the deletion of the gene or of the amount of flanking DNA that is involved.133,135

Pathophysiology and clinical presentation Although the function of neurofibromin is not completely understood, the array of clinical effects resulting from the production of abnormal neurofibromin suggests that the protein has diverse effects in a variety of tissues. Loss of neurofibromin function leads to increased cell proliferation in various tissues, ultimately resulting in the clinical hallmarks

20 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke of the disease, which include neurofibromas, skeletal anomalies, café-au-lait lesions, iris hamartomas (also known as Lisch nodules), hypertension, gliomas, and optic nerve tumors.12,134,135 At the vascular level, NF1 causes proliferation of spindle cells and smooth muscle cells, which leads to intimal thickening and fibromuscular hyperplasia.136 Cerebrovascular abnormalities were found to occur in approximately 2.5% of pediatric patients with NF1 and commonly result from stenosis or occlusion of the internal carotid, middle cerebral, or anterior cerebral artery.136,137 Later, moyamoya-like lesions may develop around the areas of stenosis, which can lead to both ischemic and hemorrhagic stroke.12,137

Diagnosis Neurofibromatosis type 1 should be suspected in children who have symptoms, such as headaches, involuntary movements, weakness, or seizures, that suggest cerebral ischemia.136 Diagnosis of NF1 is based on clinical features. Two or more of the following conditions must be present for a diagnosis of NF1: (1) ≥6 café-au-lait macules >5 mm (for prepubertal individuals) or >15 mm in diameter (for postpubertal individuals); (2) ≥2 neurofibromas of any type or 1 plexiform neurofibroma; (3) axillary or inguinal freckling; (4) optic pathway tumor; (5) ≥2 iris hamartomas; (6) distinctive osseous lesion, such as sphenoid wing dysplasia or cortical thinning of long bones; and (7) a first-degree relative with NF1 diagnosed by these criteria.133,135 Molecular testing may be useful for patients who have only 1 of the clinical findings listed above. Additionally, NF1 can be diagnosed during the prenatal period by linkage analysis or mutational screening of amniotic fluid or a chorionic villus sample.135 The differential diagnosis of NF1 includes brainstem gliomas, neurofibromatosis type 2, cauda equina syndrome, conus medullaris syndrome, low-grade astrocytoma, spinal cord hemorrhage or infarction, meningioma, and spinal epidural abscess.135

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)

Genetics The syndrome of MELAS (OMIM #540000138) is a progressive degenerative disorder associated with mutations in mitochondrial DNA (mtDNA) and a maternal pattern of inheritance; approximately 80% of patients with the disorder carry a heteroplasmic 3243A>G mutation encoding the transfer RNA (tRNA)Leu(UUR) (MT-TL1) mitochondrial gene.13,27,138-140 Other mutations on the MT-TL1 gene and mutations on other mitochondrial genes of respiratory complex I have also been noted in patients with MELAS.141 Some of these have been found to overlap with those of other mitochondrial disorders, including myoclonic epilepsy with ragged red fibers (MERRF), Leber hereditary optic neuropathy, and Leigh disease.141

Pathophysiology Mutations associated with MELAS affect tRNA function, thereby disrupting protein synthesis within the mitochondria.140 Decreased protein synthesis leads to a reduction in respiratory chain activity, inadequate generation of adenosine triphosphate, and a chronic state of insufficient cellular energy.140,141

Clinical presentation The presentation of MELAS typically reflects the name of the disorder, with features of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, but patients may also have seizures, diabetes, weakness or exercise intolerance, sensorineural hearing loss, migraine headaches, and cognitive decline.27,140,141 Stroke-like episodes in patients with MELAS have an irregular distribution (rather than a classical vascular distribution) and occur with no embolic or stenotic lesions apparent on angiography.13,141 Cortical involvement is typically asymmetric, with the parietal, occipital, and temporal lobes affected.141 The pathogenesis of these stroke-like episodes has not been fully elucidated but has been hypothesized to involve cellular energy failure secondary to abnormal oxidative phosphorylation in the brain parenchyma or cerebral vasculature. An angiopathy of small vessels, affecting the epithelium and smooth muscle of the blood vessels, which leads to vasoconstriction and disruption of the blood-brain barrier, has been described.13,27,140 Stroke-like episodes are often marked by seizures and periods of headache and vomiting, hemiparesis, cortical blindness, aphasia, and altered consciousness.27,140,141 Persistent defects occur.

21 Diagnosis The MELAS syndrome should be suspected in patients 40 years of age or younger who have had stroke-like episodes, particularly if other clinical features of MELAS are present.141 Magnetic resonance imaging is a useful diagnostic tool. Patients typically have asymmetric lesions of the parietal and occipital lobes.141 These lesions mimic ischemic lesions but are not confined to vascular territories and are restricted to the cortex.13,141 Magnetic resonance imaging findings can also include subcortical white matter lesions and generalized tissue loss.142 Magnetic resonance angiography results are usually normal.141 Cerebrospinal fluid levels of lactic acid are typically elevated in patients with MELAS.141 Proton magnetic resonance spectroscopy of the brain can be used to identify markers of metabolic abnormalities that are common in patients with MELAS, including decreased N-acetyl aspartate levels and lactic acid accumulation.140,141 Muscle biopsies from patients with MELAS often, but not always, show ragged red fibers.141 Gomori trichrome staining shows numerous basophilic inclusions.141 Areas of increased succinate dehydrogenase staining in muscle and/or blood vessel endothelium are suggestive of mitochondrial proliferation.141 Mitochondrial DNA mutational analysis may be performed by using skeletal muscle, hair follicles, buccal mucosa, urine sediment, or most commonly, peripheral blood.140,141 However, because the proportion of mutated mitochondria may vary among tissues, in some patients, mutant mitochondria may be undetectable in blood.27,141 Therefore, a negative peripheral blood screen does not necessarily rule out MELAS. The differential diagnosis for MELAS includes a variety of conditions: other mtDNA syndromes, antiphospholipid syndrome, antithrombin III deficiency, second- or third-degree atrioventricular block, dilated or hypertrophic cardiomyopathy, hypoparathyroidism, long- or medium- chain acyl-coenzyme A dehydrogenase deficiency, mitochondrial DNA polymerase deficiency, Pearson syndrome, and Wolff- Parkinson-White syndrome.140

COL4A1 gene mutations The COL4A1 gene encodes for the a1 chain of type IV collagen, a protein found in basement membranes, including those of the vasculature.144,145 Mutations in this gene (OMIM #120130143) may compromise the structural integrity of vascular basement membranes and thereby render the vessels susceptible to disruption, particularly in the presence of environmental stressors or other risk factors, and may also cause swelling of vascular endothelial cells.145 Such mutations may predispose individuals to ischemic and/or hemorrhagic stroke.144-146 Other tissues, including the kidneys, skin, and eyes, may also be affected.144,146-148 The variety of phenotypes seen in individuals with COL4A1 mutations results from interactions between genetic and environmental factors. Autosomal dominant porencephaly has been noted in a number of families with COL4A1 mutations, along with leukoencephalopathy, lacunar infarcts, microhemorrhages, and macrohemorrhages.145,146 An autosomal dominant condition marked by leukoencephalopathy, infantile hemiplegia, and retinal arteriolar tortuosities has been posited to be related to a COL4A1 mutation.146,149 Another distinct phenotype noted in individuals with COL4A1 mutations is characterized by developmental abnormalities of the anterior eye chamber, leukoencephalopathy, ischemic lacunar infarcts, and microhemorrhages.147 Finally, Plaisier et al148 found COL4A1 mutation to be associated with a syndrome of hereditary angiopathy with nephropathy, , and muscle cramps (HANAC). Conditions associated with COL4A1 mutations are likely under-recognized, particularly in light of the heterogeneity of clinical phenotypes. COL4A1 screening has been suggested in cases of familial porencephaly or childhood-onset stroke, particularly if retinal arteriolar tortuosity is noted in either the patient or his/her family members.144 However, given that health and genetic counseling will be vitally important to COL4A1 mutation carriers, better delineation of indications for genetic screening is needed.144,150

Inherited abnormalities of blood coagulation A variety of inherited coagulation abnormalities can cause ischemic and hemorrhagic strokes. Disturbances in the functionality and/or levels of prothrombin, factor V, protein C, protein S, and antithrombin III are associated with single-gene mutations and increase an individual’s risk of thrombosis; however, their roles in ischemic stroke are still debated.13,27,151-155 These disorders should be considered in patients (particularly young patients) with otherwise unexplained ischemic stroke, and the workup in such patients should include testing to detect the most common hereditary coagulation abnormalities.

22 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Treatment of single-gene disorders associated with stroke Among the disorders discussed herein, currently, only FD and SCD have potentially ameliorative/curative treatments available. The other disorders (ie, CADASIL, CARASIL, RVCL, MMD, Marfan syndrome, NF1, and MELAS) have no such treatments; rather, therapies are generally aimed at managing a patient’s specific symptoms and providing supportive care.12,70,82,86,141,156-159 Psychological and/or genetic counseling should be provided to patients and their families.12,156,157 Identification and management of risk factors for atherosclerosis, along with general maintenance of cerebrovascular health and prevention of stroke, are important in these patients. Such measures may include treatment with or other antiplatelet drugs, , antihypertensive agents, and fibrinolytic agents.12,82,83,86,157 and ergotamines should be avoided in patients with CADASIL and related disorders.157,160 Some clinicians and patients have found that coenzyme Q10 at doses of 200 to 600 mg/d may provide some symptomatic relief and stabilization in patients with CADASIL, but this is largely anecdotal.157,161 Anticoagulation therapy is often avoided in patients with CADASIL, MMD, or COL4A1 mutations because of the associated risk of hemorrhage and microbleeds.12,162,163 Various surgical therapies may provide long-term protection from ischemic stroke and cerebral bleeds in patients with MMD. Procedures such as encephalo-duro-arterio-synangiosis/encephalo-duro-arterio-myo-synangiosis and extracranial-intracranial bypass may reduce the development of additional moyamoya vessels, improve hemispheric perfusion, and prevent subsequent strokes.164-167 Antiplatelet agents should be used cautiously because of the risk of cerebral bleeds, particularly in the latter stages of the disease if the moyamoya vessels have not been treated with some type of bypass.12 Aggressive control of other vascular risk factors is also recommended. Among patients with NF1, surgical revascularization may also be useful in those who have moyamoya syndrome, and other surgical procedures/angioplasty may help reduce the risk of hemorrhage.159 A report from one study suggested that supplementation with l-arginine may improve endothelial function, as measured by flow-mediated vasodilation, in patients with MELAS.168

Treatment of Fabry disease Two types of enzyme replacement therapy (ERT) are available103,169 to replace deficient a-galactosidase A in patients with FD: agalsidase alfa (Replagal®; Shire Human Genetic Therapies, Hampshire, UK)170 and agalsidase beta (Fabrazyme®; Genzyme Corporation, Cambridge, Massachusetts, USA).171 These ERT variants are produced in different ways and differ in their glycosylation patterns, suggested dosages, and suggested infusion times.116 Results of research to date suggest that ERT appears to slow the decline of renal function by decreasing glycosphingolipid storage and proteinuria and by improving creatinine clearance.96,103,116,169 Results from double-blind (20-week) and open-label (6-month) extension studies suggested that ERT was associated with clearance of globotriaosylceramide deposits in the skin, heart, and microvasculature.169 Because ERT for FD has been available only since 2001, its long-term effects on the natural history of the disease are not known.103 The use of ERT for FD may also stabilize or cause regression of cardiomyopathy and may normalize cardiac rhythm variability.116 However, success of ERT in this regard likely depends on the extent of irreversible cardiovascular damage that occurred before ERT began, as was illustrated by the results of a 12-month study in which the degree of left ventricle hypertrophy before initiation of ERT correlated inversely with the success of ERT.103,172 Additionally, ERT appears to be useful in decreasing the severity of neuropathic pain, but pain medications may still be needed.103,116 Other noted effects of ERT include reduction of gastrointestinal tract symptoms, normalization of sweating, cessation of hearing loss progression, and improvement in quality of life.116 Although ERT can improve the function of the cerebral vasculature in patients with FD, it does not appear to markedly reduce stroke risk in the first few years following initiation of therapy in adulthood.103,116 However, relatively few patients have been studied, and the long-term effects of ERT on the risk of stroke may take several years to determine.103 Studies are needed to determine whether early initiation of ERT in children (ie, before irreversible structural changes in the vasculature have occurred) is more effective than is ERT begun later in life.103 Current guidelines for the use of ERT in FD173 suggest that it be initiated in men at the time of diagnosis. For boys, ERT for FD should begin when significant symptoms develop or at 10 to 13 years of age in asymptomatic patients. In girls and women, ERT should begin when significant symptoms develop or if there is evidence for progression of organ involvement.

23 Patients with FD may also be treated with a variety of adjunctive and preventive therapies to manage their specific symptoms, and prophylactic therapy may be used to prevent complications such as TIA and stroke (Table 4).96,102,103,169 Other therapies, including pharmacological chaperones to promote the normal folding and trafficking of proteins,103 are currently in development. Table 4. Options for the Prophylaxis and Management of Symptoms in Patients With Fabry Disease96,102,103,173

Symptom(s) or Organ/System Affected Treatments Cardiac ACE inhibitors, statins, calcium channel blockers, verapamil, PTSMA, permanent cardiac pacing, bypass surgery, cardiac transplantation Dermatologic Laser treatments, liquid nitrogen treatments Gastrointestinal tract Dietary changes, H2 blockers, pancrelipase, metoclopramide, loperamide Neuropathic pain AEDs (eg, carbamazepine, gabapentin, pregabalin, lamotrigine, phenytoin, topiramate), narcotics (in select patients), avoidance of circumstances that promote pain crises Otologic Hearing aids, cochlear implants Pulmonary Bronchodilators, cessation of smoking Renal ACE inhibitors, ARBs, dialysis, kidney transplantation Stroke prophylaxis Aspirin, clopidogrel, long-acting , ACE inhibitors, ARBs, statins, adequate intake of vitamins B12, B6, C, and folate Abbreviations: ACE, angiotensin-converting enzyme; PTSMA, percutaneous transluminal septal myocardial ablation; AED, antiepileptic drug; ARB, angiotensin receptor blocker.

Treatment of sickle cell disease Bone marrow transplantation (BMT) may be curative in patients with SCD.174 Although its effects on the risk of stroke are not entirely clear, results from one study showed that in 22 patients who received BMT, after at least 2 years of follow-up, none had significant SCD-related CNS events after transplantation, and most patients had stabilization of underlying cerebral vasculopathy.174,175 It is important to note that BMT is associated with serious risks including graft rejection, graft-versus-host disease, seizures, and .174 Transfusion therapy may reduce the risk of recurrent stroke to as low as 10% in patients with SCD.174 It is particularly useful in patients who are identified by transcranial Doppler ultrasonography as being at high risk for stroke.176 In red cell exchange transfusion, the patient’s red blood cells are removed and replaced by normal, exogenous red blood cells.177 As a result, sickle cells are removed and cannot participate in new vaso-occlusive events, the oxygen-carrying capacity of the blood is increased, and blood viscosity and the risk of hemolytic complications are decreased. However, red cell transfusion is more expensive and requires more blood than simple transfusion does.174 Other potential disadvantages of transfusion therapy include alloimmunization and iron overload, the latter of which may occur after years of transfusion therapy.174 Hydroxyurea (HU) is a chemotherapeutic agent that elevates the patient’s percentage of fetal hemoglobin (HbF).174 In patients with SCD, HbF inhibits the polymerization of HbS, thereby preventing the sickling of red blood cells.13 Certain genetic factors, including b-globin haplotype and a locus on chromosome 6q, may influence the response of a patient’s HbF level to HU therapy.121,178 Treatment with HU may increase red blood cell survival; reduce levels of monocytes, neutrophils, and reticulocytes; decrease Doppler flow velocities in children with SCD; and prevent stroke.121,179-182 Typically, HU therapy is initiated at a dosage of 15 mg/kg/d and titrated upward in increments of 5 mg/kg/d every 8 to 12 weeks to a maximum dosage of ~30 mg/kg/d.174 Several other potential therapies for patients with SCD are currently under investigation. These include inducers of HbF (decitabine, butyrate, erythropoietin); agents that prevent red blood cell dehydration (ICA-17043 [senicapoc], magnesium pidolate); vasodilators (inhaled NO, arginine, sildenafil, statins); anti-adhesive agents (sulfasalazine and other nuclear factor-kB inhibitors, poloxamer 188); secretory phospholipase A2 inhibitors; antithrombotic agents; immunomodulators (pomalidomide, lenalidomide); and corticosteroids.121,183,184 Nix-0699, an herbal preparation that has been proposed to act by increasing HbS oxygen affinity, is also under investigation for potential use in SCD.183 Drug combinations (eg, HbF inducer plus a vasodilator or an agent that prevents either endothelial adhesion or red blood cell dehydration) may also be useful, but further studies are needed to determine the best therapeutic combinations to individualize treatment for each patient’s specific symptoms.183

24 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

Case studies

CADASIL case study A 45-year-old white woman with a history of migraine headaches for the past 20 years noted an increase in headache severity and frequency during the past 3 to 4 years. She also recently had developed frequent word-finding problems and intermittent numbness/weakness, usually involving her left arm and leg but occasionally involving her right side. She also reported short- term memory problems. Her husband and friends recently noted some subtle personality changes. Her past medical history was significant for headaches, occasional urinary tract infections, and mild hypertension. Her medications for headaches included ibuprofen and occasional sumatriptan, and she also took multivitamins. Physical examination revealed a well-nourished white woman who was in no acute distress. Vital sign measurements and results of examinations of her heart, extremities, and skin were normal, and she had no carotid bruits. Neurologic examination showed her to be slightly anxious; her speech was slightly hesitant, with rare word-finding problems. Cranial nerve examination revealed very slight dysarthria. Motor examination showed very subtle weakness in the left arm and leg, but sensation and coordination were intact. Deep tendon reflexes were brisk bilaterally; toes were downgoing to plantar stimulation bilaterally. Gait was normal. Results from routine laboratory studies were normal. A fasting lipid panel showed a low-density lipoprotein level (LDL) of 125 mg/dL. High-density lipoprotein and triglyceride levels were normal. A head CT scan showed subtle deep white matter hypodensities. An MRI scan showed diffuse white matter ischemic changes involving the periventricular regions and the anterior temporal lobes; diffusion-weighted imaging sequences were negative for acute infarctions. There was no abnormal contrast enhancement. Magnetic resonance angiography was negative for large-vessel disease. On further questioning, the patient noted that her mother had chronic headaches, as well as strokes and TIAs, in her 40s and 50s. The patient underwent genetic testing and was found to have a typical mutation in exon 3 of the Notch3 gene, indicating CADASIL. She was treated with low-dose (81 mg/d) aspirin for stroke prevention, as well as atorvastatin (40 mg/d) for her elevated LDL level. She received a trial of coenzyme Q10 (200 mg twice a day) and reported a decline in her headaches and TIAs. She was sent to a genetic counselor for further advice about having her children tested for Notch3 gene mutations.

FD case study A 31-year-old man was referred to a neuromuscular specialist for back pain. Findings from his general and neurologic examinations were normal at that time. Workup included imaging studies, which documented renal cysts; a nephrologist was consulted. An elevated plasma creatinine level was noted, and renal biopsy was performed. His medical history was significant for childhood-onset pain in the hands and feet, exacerbated by hot weather, illness, and fever. At age 13 years he had significant gastrointestinal dysmotility symptoms (eg, postprandial bloating, explosive diarrhea). Extensive workup, including upper endoscopy with biopsies, colonoscopy, and gastric-emptying studies, yielded no diagnosis. He was treated with rimantadine as needed. Other medications included nonsteroidal anti-inflammatory drugs for pain. Renal biopsy findings, including focal segmental glomerulosclerosis, focal hyalinosis, and severe tubular atrophy, were consistent with FD. Electron microscopy showed extensive deposition of multilayered, whorled, lamellated membrane structures (zebra bodies), primarily in podocytes. Podocyte foot process effacement was moderate and involved approximately 50% to 60% of the membrane surface. Further laboratory evaluation documented significant proteinuria (1.7 g/d). Plasma creatinine levels varied between 2.5 and 3.0 mg/dL. Testing for a-galactosidase showed residual enzymatic activity of 2%. Molecular testing documented an a-galactosidase mutation (I242F), which is not inducible in tissue culture, thus precluding patient enrollment in studies of small molecular (chaperone) therapies. Molecular diagnosis of FD allowed for familial genetic risk assessment and counseling. The patient’s mother was identified as having FD and had a stroke before she could be seen in the clinic. Her care continues with the assumption that she is at risk for significant organ dysfunction. Other affected family members follow an X-linked inheritance pattern. Two of the mother’s 5 siblings (both female) carried the FD mutation, but her one brother did not. The patient (proband) has one sister who also tested positive for the mutation, as did her asymptomatic 5-year-old son, who will be monitored closely and possibly treated with ERT.

25 With ERT (agalsidase beta) and angiotensin-converting enzyme inhibitor therapy, the patient’s proteinuria improved (<500 mg/d), but his plasma creatinine level increased to >4.0 mg/dL, and his creatinine clearance decreased from 28 mL/min/1.73m2 before beginning ERT to <20 mL/min/1.73m2 He required renal transplantation 2 years after FD diagnosis, presumably because of significant proteinuria and irreversible renal damage. Before transplantation, he received epoetin alfa for anemia of chronic disease, which was presumed to be secondary to renal insufficiency. He continues to take aspirin (81 mg/d) as antiplatelet therapy for stroke prevention. After undergoing transplantation, the patient continued on ERT; other medications and supplements included co-trimoxazole, mycophenolate, ergocalciferol, famciclovir, magnesium oxide, omeprazole, calcium carbonate, potassium phosphate, and tacrolimus. His renal function normalized after renal transplantation. Echocardiogram findings, including posterior wall (9 mm) and interventricular septal wall (9 mm) thickness, were normal. Cardiac MRI showed delayed enhancement in the lateral wall, suggestive of early glycosphingolipid deposition. The patient will continue to be screened for multisystem dysfunction. He has no history of palpitations or cardiac arrhythmia, and results from cardiac stress testing and 48-hour Holter monitoring remain normal. Pulmonary function test results are normal. He has had no TIA or stroke-like events, and the patient’s cranial MRI is normal, except for scattered subcortical increased T2 signal foci. Prothrombotic panel testing was performed to investigate for potential comorbidities of coagulation. The patient’s bone mass for both hips and the lumbar spine is approximately 1 standard deviation below means for his age and gender. He is receiving vitamin D and calcium supplementation. Agalsidase beta antibody testing is positive with increasing titers, now maximally 1:3200. Modest increases in antibody titers are not uncommon in FD patients treated with ERT, and it is unclear whether such increases decrease the effectiveness of ERT. No change in ERT dosing was made.

MELAS case study A 48-year-old, right-handed woman in good health was admitted to the emergency department with a first generalized seizure. Her medical history was significant for progressive sensorineural hearing loss and tinnitus for 2 years, adolescent migraine, focal sclerosing glomerulonephritis, and Lyme disease (treated with oral doxycycline 4 years earlier). She was taking losartan and had no allergies or history of smoking. She took no illicit drugs and used alcohol only socially. Her developmental history was normal. Two weeks before hospital admission, she seemed to misinterpret environmental sounds, noting construction, gong, and bird chirping sounds. There was no clear indication of hallucination. Her husband noted that she had unusual behaviors and some mental slowing during this period. On the day of admission, the patient was confused and flustered, seemed to lose her hearing completely, and had numbness in her left leg. She had had a 5-minute generalized tonic-clonic seizure on the way to the emergency department. Findings of a general examination of the patient at presentation were unremarkable. Neurologic examination revealed abnormal affect but normal speech, language, attention, and memory. She had no motor deficit and had left leg numbness with extinction of double simultaneous stimuli. Cranial MRI showed an acute right middle cerebral artery region stroke with unusual borders, which suggested a metabolic etiology rather than a major artery territory insult. Scattered white matter T2 foci were noted in the periventricular region. Basal ganglia were normal. Results from MRA were normal and showed no evidence of large-vessel disease; magnetic resonance spectroscopy (MRS) was not performed. An electroencephalogram documented bilateral temporal slowing with scattered spikes. Results from routine laboratory tests, a fasting lipid panel, and cardiac evaluations were unremarkable. After the patient was released from the hospital, genetic testing revealed a 3243A>G mutation, indicating MELAS. The patient returned to the clinic for follow-up and collection of an extended family history. Her 3 brothers and 1 sister were alive and well without multisystem problems suggestive of metabolic disorders. The patient’s mother was 78 years old and healthy, with only a history of hyperlipidemia. The mother had 12 siblings (all deceased), including 2 sisters who had short stature but no neuromedical or multisystem disorders. There was no other family history of significant neuromedical disease or early death. The patient’s 2 teenage sons both were healthy but obligate carriers. The 3243A>G mutation was confirmed in both sons, who received genetic counseling about the maternal inheritance of the disorder and their potential risk for MELAS- associated symptoms.

26 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

The patient was treated with anticonvulsants, aspirin, and a vitamin cofactor regimen that included coenzyme Q10, antioxidants, and B vitamins. She did well for 6 months but then sustained a second metabolic stroke, which was clinically characterized by profound expressive language failure and transient right hand weakness. Motor symptoms resolved within hours; cognition, behavior, and mood were normal. Cranial MRI showed acute T2 abnormalities throughout the left hemisphere, not respecting vessel territory and appearing far more extensive than was suggested by the clinical deficit. Diffusion-weighted imaging results were normal, and MRS showed a biparietal cortical increase in lactate. Prior right temporal stroke appeared chronic on imaging. With intensive speech and language therapy, the patient slowly recovered expressive verbal and written skills but never returned to normal function. She remained at home, carried out simple household tasks, stopped driving, and took frequent naps. Her regimen of vitamin cofactors and anticonvulsants was eventually tapered and stopped. Three years after her initial presentation, the patient had a third stroke. Again, clinical onset of the stroke was marked by confusion and language failure, but its metabolic territory extended to involve both hemispheres despite intravenous alanine and metabolic support. The patient became withdrawn and unresponsive. No seizures were observed; electroencephalogram was generally slow. Eventually, she was taken off life support, after a prolonged intensive care unit stay (secondary to cardiopulmonary complications). Later genetic testing of the patient’s mother showed that she did not carry the 3243A>G mutation. Therefore, the proband was determined to be a new mutation carrier. Her sons have remained healthy over the subsequent 5 years, except for mild gastrointestinal dysmotility symptoms in one and migraine headaches in the other. They receive vitamin cofactors and are monitored closely. No other relatives are at genetic risk for MELAS, and family members have been counseled to clarify this point.

Conclusions Determining the etiology of stroke is important in order to reduce the risk of stroke recurrence. Single-gene disorders, such as the ones discussed herein, are rare but should be considered in cases of cryptogenic stroke, particularly in young patients with no or few conventional risk factors for stroke. Although many of these disorders currently have no curative or ameliorative treatments available, early identification allows for interventions to maintain cardiovascular and neurovascular health, along with the provision of symptom management and supportive care. Early diagnosis of FD and SCD is especially important, as the timing of initiation of treatment for these disorders may affect a patient’s prognosis and the risk of stroke and its recurrence.

27 References

1. Stroke facts. Centers for Disease Control and Prevention Web site. http://www.cdc.gov/stroke/facts.htm. Updated January 28, 2010. Accessed February 10, 2010. 2. Global burden of stroke. World Health Organization Web site. http://www.who.int/cardiovascular_diseases/en/cvd_ atlas_15_burden_stroke.pdf. Accessed May 26, 2009. 3. Heart disease and stroke statistics: 2010 update at-a-glance. American Heart Association Web site. http://www. americanheart.org/presenter.jhtml?identifier=3000090. Accessed April 29, 2010. 4. Women and stroke. The Stroke Association Web site. http://www.stroke.org.uk/information/our_publications/factsheets/ women.html. Accessed December 9, 2009. 5. Lloyd-Jones D, Adams R, Carnethon M, et al. Heart disease and stroke statistics 2009 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2009;119(3):e21-e181. 6. Guercini F, Acciarresi M, Agnelli G, Paciaroni M. Cryptogenic stroke: time to determine aetiology. J Thromb Haemost. 2008;6(4):549-554. 7. Lisovoski F, Rousseaux P. Cerebral infarction in young people. A study of 148 patients with early cerebral angiography. J Neurol Neurosurg Psychiatry. 1991;54(7):576-579. 8. Arnold M, Halpern M, Meier N, et al. Age-dependent differences in demographics, risk factors, co-morbidity, etiology, management and clinical outcomes of acute ischemic stroke. J Neurol. 2008;255(10):1503-1507. 9. Carod-Artal FJ, Nunes SV, Portugal D, Silva TVF, Vargas AP. Ischemic stroke subtypes and thrombophilia in young and elderly Brazilian stroke patients admitted to a rehabilitation hospital. Stroke. 2005;36(9):2012-2014. 10. Eggers AE. A new theory of cryptogenic stroke and its relationship to patent foramen ovale; or, the puzzle of the missing extra risk. Med Hypotheses. 2006;67(5):1072-1075. 11. Gállego J, Martinez Vila E, Muñoz R. Patients at high risk for ischemic stroke: identification and actions. Cerebrovasc Dis. 2007;24(suppl 1):49-63. 12. Razvi SS, Bone I. Single gene disorders causing ischaemic stroke. J Neurol. 2006;253(6):685-700. 13. Dichgans M. Genetics of ischaemic stroke. Lancet Neurol. 2007;6(2):149-161. 14. Ninomiya JK, L’Italien G, Criqui MH, Whyte JL, Gamst A, Chen RS. Association of the metabolic syndrome with history of myocardial infarction and stroke in the Third National Health and Nutrition Examination Survey. Circulation. 2004;109(1):42-46. 15. Stroke risk factors. American Heart Association Web site. http://www.americanheart.org/print_presenter. jhtml?identifier=4716. Accessed March 5, 2010. 16. Fullerton HJ, Elkins JS, Johnston SC. Pediatric stroke belt: geographic variation in stroke mortality in US children. Stroke. 2004;35(7):1570-1573. 17. Cenral nervous system vasculitis. The Johns Hopkins Vasculitis Center Web site. http://vasculitis.med.jhu.edu/typesof/ cns.html. Accessed January 26, 2010. 18. Xavier AR, Qureshi AI, Kirmani JF, Yahia AM, Bakshi R. Neuroimaging of stroke: a review. South Med J. 2003;96(4):367-379. 19. Amarenco P. Underlying pathology of stroke of unknown cause (cryptogenic stroke). Cerebrovasc Dis. 2009;27(suppl 1):97- 103. 20. Touzé E. Can aortic MRI be used instead of transesophageal echocardiography in patients with ischaemic stroke? J Neurol Neurosurg Psychiatry. 2008;79(5):489. 21. Cabanes L, Mas JL, Cohen A, et al. Atrial septal aneurysm and patent foramen ovale as risk factors for cryptogenic stroke in patients less than 55 years of age. A study using transesophageal echocardiography. Stroke. 1993;24(12):1865-1873. 22. Ortiz G, Kock S, Romano JG, Forteza AM, Rabinstein AA. Mechanisms of ischemic stroke in HIV-infected patients. Neurology. 2007;68(16):1257-1261. 23. Rabinstein AA. Stroke in HIV-infected patients: a clinical perspective. Cerebrovasc Dis. 2003;15(1-2):37-44. 24. Michelson DJ, Ashwal S. The pathophysiology of stroke in mitochondrial disorders. Mitochondrion. 2004;4(5-6):665-674. 25. Finsterer J. Central nervous system manifiestations of mitochondrial disorders. Acta Neurol Scand. 2006;114(4):217-238.

28 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

26. Testai FD, Gorelick PB. Inherited metabolic disorders and stroke part 2: homocystinuria, organic acidurias, and urea cycle disorders. Arch Neurol. 2010;67(2):148-153. 27. Flossmann E. Genetics of ischaemic stroke; single gene disorders. Int J Stroke. 2006;1(3):131-139. 28. Testai FD, Gorelick PB. Inheritied metabolic disorders and stroke part 1: Fabry disease and mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. Arch Neurol. 2010;67(1):19-24. 29. Fellgiebel A, Müller MJ, Ginsberg L. CNS manifestations of Fabry’s disease. Lancet Neurol. 2006;5(9):791-795. 30. Ginsberg L, Manara R, Valentine AR, Kendall B, Burlina AP. Magnetic resonance imaging changes in Fabry disease. Acta Paediatr Suppl. 2006;95(451):57-62. 31. Fellgiebel A, Albrecht J, Dellani PR, Schermuly I, Stoeter P, Müller MJ. Quantification of brain tissue alterations in Fabry disease using diffusion-tensor imaging. Acta Paediatr Suppl. 2007;96(455):33-36. 32. OMIM #125310 Cerebral arteriopathy, autosomal dominant, with subcortical infarcts and leukoencephalopathy; CADASIL. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/omim/125310. Accessed May 27, 2010. 33. Joutel A, Corpechot C, Ducros A, et al. Notch3 mutations in CADASIL, a hereditary adult-onset condition causing stroke and dementia. Nature. 1996;383(6602):707-710. 34. Joutel A, Andreux F, Gaulis S, et al. The ectodomain of the Notch3 receptor accumulates within the cerebrovasculature of CADASIL patients. J Clin Invest. 2000;105(5):597-605. 35. Joutel A, Favrole P, Labauge P, et al. Skin biopsy immunostaining with a Notch3 monoclonal antibody for CADASIL patients. Lancet. 2001;358(9298):2049-2051. 36. Guidetti D, Casali B, Mazzei RL, Dotti MT. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Clin Exp Hypertens. 2006;28(3-4):271-277. 37. Chabriat H, Vahedi K, Iba-Zizen MT, et al. Clinical spectrum of CADASIL: a study of 7 families. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Lancet. 1995;346(8980):934-939. 38. Chabriat H, Mrissa R, Levy C, et al. Brain stem MRI signal abnormalities in CADASIL. Stroke. 1999;30(2):457-459. 39. Vahedi K, Chabriat H, Levy C, Joutel A, Tournier-Lasserve E, Bousser M-G. Migraine with aura and brain magnetic resonance imaging abnormalities in patients with CADASIL. Arch Neurol. 2004;61(8):1237-1240. 40. Dichgans M, Mayer M, Uttner I, et al. The phenotypic spectrum of CADASIL: clinical findings in 102 cases.Ann Neurol. 1998;44(5):731-739. 41. Roine S, Harju M, Kivelä TT, et al. Ophthalmologic findings in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: a cross-sectional study. Ophthalmology. 2006;113(8):1411-1417. 42. Bohlega S, Al Shubili A, Edris A, et al. CADASIL in Arabs: clinical and genetic findings. BMC Med Genet. 2007;8:67. 43. O’Sullivan M, Jarosz JM, Martin RJ, Deasy N, Powell JF, Markus HS. MRI hyperintensities of the temporal lobe and external capsule in patients with CADASIL. Neurology. 2001;56(5):628-634. 44. Dichgans M, Holtmannspötter M, Herzog J, Peters N, Bergmann M, Yousry TA. Cerebral microbleeds in CADASIL: a gradient-echo magnetic resonance imaging and autopsy study. Stroke. 2002;33(1):67-71. 45. Lesnick Oberstein SA, van den Boom R, van Buchem MA, et al. Cerebral microbleeds in CADASIL. Neurology. 2001;57(6):1066-1070. 46. Ebke M, Dichgans M, Bergmann M, et al. CADASIL: skin biopsy allows diagnosis in early stages. Acta Neurol Scand. 1997;95(6):351-357. 47. Markus HS, Martin RJ, Simpson MA, et al. Diagnostic strategies in CADASIL. Neurology. 2002;59(8):1134-1138. 48. Mayer M, Straube A, Bruening R, et al. Muscle and skin biopsies are a sensitive diagnostic tool in the diagnosis of CADASIL. J Neurol. 1999;246(7):526-532. 49. Pandey T, Abubacker S. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: an imaging mimic of multiple sclerosis. A report of two cases. Med Princ Pract. 2006;15(5):391-395. 50. Young WB, Silberstein SD. Migraine: spectrum of symptoms and diagnosis. Continuum Lifelong Learning Neurol. 2006;12(6):67-86.

29 51. Williamson EE, Chukwudelunzu FE, Meschia JF, Witte RJ, Dickson DW, Cohen MD. Distinguishing primary angiitis of the central nervous system from cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: the importance of family history. Arthritis Rheum. 1999;42(10):2243-2248. 52. Thomas NJ, Morris CM, Scaravilli F, et al. Hereditary vascular dementia linked to Notch3 mutations. Ann NY Acad Sci. 2000;903:293-298. 53. Vahedi K, Tournier-Lasserve E, Vahedi K, Chabriat H, Bousser MG. An additional monogenic disorder that masquerades as multiple sclerosis. Am J Med Genet. 1996;65(4):357-358. 54. Peters N, Opherk C, Danek A, Ballard C, Herzog J, Dichgans M. The pattern of cognitive performance in CADASIL: a monogenic condition leading to subcortical ischemic vascular dementia. Am J Psychiatry. 2005;162(11):2078-2085. 55. OMIM #600142 Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy; CARASIL. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/omim/600142. Accessed May 27, 2010. 56. Hara K, Shiga A, Fukutake T, et al. Association of HTRA1 mutations and familial ischemic cerebral small-vessel disease. N Engl J Med. 2009;360(17):1729-1739. 57. Leask A, Abraham DJ. TGF-beta signaling and the fibrotic response.FASEB J. 2004;18(7):816-827. 58. Schönherr E, Järveläinen HT, Sandell LJ, Wight TN. Effects of platelet-derived growth factor and transforming growth factor-beta 1 on the synthesis of large versican-like chondroitin sulfate proteoglycan by arterial smooth muscle cells. J Biol Chem. 1991;266(26):17640-17647. 59. Zheng DM, Xu FF, Gao Y, Zhang H, Han SC, Bi GR. A Chinese pedigree of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL): clinical and radiological features. J Clin Neurosci. 2009;16(6):847- 849. 60. Oide T, Nakayama H, Yanagawa S, Ito N, Ikeda S, Arima K. Extensive loss of arterial medial smooth muscle cells and mural extracellular matrix in cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL). Neuropathology. 2008;28(2):132-142. 61. Arima K, Yanagawa S, Ito N, Ikeda S. Cerebral arterial pathology of CADASIL and CARASIL (Maeda syndrome). Neuropathology. 2003;23(4):327-334. 62. Fukutake T, Hirayama K. Familial young-adult-onset arteriosclerotic leukoencephalopathy with alopecia and lumbago without arterial hypertension. Eur Neurol. 1995;35(2):69-79. 63. Francis J, Raghunathan S, Khanna P. The role of genetics in stroke. Postgrad Med J. 2007;83(983):590-595. 64. Maeda S, Nakayama H, Isaka K, Aihara Y, Nemoto S. Familial unusual encephalopathy of Binswanger’s type without hypertension. Folia Psychiatr Neurol Jpn. 1976;30(2):165-177. 65. Yanagawa S, Ito N, Arima K, Ikeda S. Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy. Neurology. 2002;58(5):817-820. 66. OMIM #192315 Vasculopathy, retinal, with cerebral leukodystrophy. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/omim/192315. Accessed May 27, 2010. 67. Richards A, van den Maagdenberg AMJM, Jen JC, et al. C-terminal truncations in human 3′-5′ DNA exonuclease TREX1 cause autosomal dominant retinal vasculopathy with cerebral leukodystrophy. Nat Gen. 2007;39(9):1068-1070. 68. Kavanagh D, Spitzer D, Kothari PH, et al. New roles for the major human 3′-5′ exonuclease TREX1 in human disease. Cell Cycle. 2008;7(12):1718-1725. 69. Stam AH, Haan J, van den Maagdenberg AMJM, Ferrari MD, Terwindt GM. Migraine and genetic and acquired vasculopathies. Cephalalgia. 2009;29(9):1006-1017. 70. Jen J, Cohen AH, Yue Q, et al. Hereditary endotheliopathy with retinopathy, nephropathy and stroke (HERNS). Neurology. 1997;49(5):1322-1330. 71. Ophoff RA, DeYoung J, Service SK, et al. Hereditary vascular retinopathy, cerebroretinal vasculopathy, and hereditary endotheliopathy with retinopathy, nephropathy, and stroke map to a single locus on chromosome 3p21.1-p21.3. Am J Hum Genet. 2001;69(2):447-453. 72. Terwindt GM, Haan J, Ophoff RA, et al. Clinical and genetic analysis of a large Dutch family with autosomal dominant vascular retinopathy, migraine and Raynaud’s phenomenon. Brain. 1998;121(pt 2):303-316.

30 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

73. Weil S, Reifenberger G, Dudel C, Yousry TA, Schriever S, Noachtar S. Cerebroretinal vasculopathy mimicking a brain tumor: a case of a rare hereditary syndrome. Neurology. 1999;53(3):629-631. 74. OMIM %252350 Moyamoya disease 1; MYMY1. National Center for Biotechnology Information Web site. http://www.ncbi. nlm.nih.gov/omim/252350. Accessed May 27, 2010. 75. Inoue TK, Ikezaki K, Sasazuki T, Matsushima T, Fukui M. Linkage analysis of moyamoya disease on chromosome 6. J Child Neurol. 2000;15(3):179-182. 76. Ikeda H, Sasaki T, Yoshimoto T, Fukui M, Arinami T. Mapping of a familial moyamoya disease gene to chromosome 3p24.2-p26. Am J Hum Genet. 1999;64(2):533-537. 77. Sakurai K, Horiuchi Y, Ikeda H, et al. A novel susceptibility locus for moyamoya disease on chromosome 8q23. J Hum Genet. 2004;49(5):278-281. 78. OMIM %607151 Moyamoya disease 2; MYMY2. National Center for Biotechnology Information Web site. http://www.ncbi. nlm.nih.gov/omim/607151. Accessed May 27, 2010. 79. OMIM %608796 Moyamoya disease 3. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih. gov/omim/608796. Accessed May 27, 2010. 80. Mineharu Y, Liu W, Inoue K, et al. Autosomal dominant moyamoya disease maps to chromosome 17q25.3. Neurology. 2008;70(24 pt 2):2357-2363. 81. Yamauchi T, Tada M, Houkin K, et al. Linkage of familial moyamoya disease (spontaneous occlusion of the circle of Willis) to chromosome 17q25. Stroke. 2000;31(4):930-935. 82. Ishimori ML, Cohen SN, Hallegua DS, Moser FG, Weisman MH. Ischemic stroke in a postpartum patient: understanding the epidemiology, pathogenesis, and outcome of moyamoya disease. Semin Arthritis Rheum. 2006;35(4):250-259. 83. Sucholeiki R, Chawla J. Moyamoya disease. eMedicine Web Site. http://emedicine.medscape.com/article/1180952- overview. Accessed May 27, 2010. 84. Burke GM, Burke AM, Sherma AK, Hurley MC, Batjer HH, Bendok BR. Moyamoya disease: a summary. Neurosurg Focus. 2009;26(4):E11. 85. Spengos K, Tsivgoulis G, Toulas P, Vemmos K, Vassilopoulos D, Spengos M. Hyperventilation-enhanced chorea as a transient ischaemic phenomenon in a patient with moyamoya disease. Eur Neurol. 2004;51(3):172-175. 86. Scott RM, Smith ER. Moyamoya disease and moyamoya syndrome. N Engl J Med. 2009;360(12):1226-1237. 87. Saeki N, Nakazaki S, Kubota M, et al. Hemorrhagic type moyamoya disease. Clin Neurol Neurosurg. 1997;99(suppl 2):S196-S201. 88. Fukui M. Guidelines for the diagnosis and treatment of spontaneous occlusion of the circle of Willis (moyamoya disease). Clin Neurol Neurosurg. 1997;99(suppl 2):S238-S240. 89. Storen EC, Wijdicks EF, Crum BA, Schultz G. Moyamoya-like vasculopathy from cocaine dependency. AJNR Am J Neuroradiol. 2000;21(6):1008-1010. 90. OMIM #301500 Fabry disease. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/ entrez/dispomim.cgi?id=301500. Accessed March 8, 2010. 91. Bishop DF, Kornreich R, Desnick RJ. Structural organization of the human alpha-galactosidase A gene: further evidence for the absence of a 3′ untranslated region. Proc Natl Acad Sci USA. 1988;85(11):3903-3907. 92. MacDermot KD, Holmes A, Miners AH. Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 98 hemizygous males. J Med Genet. 2001;38(11):750-760. 93. Fischer EG, Moore MJ, Lager DJ. Fabry disease: a morphologic study of 11 cases. Mod Pathol. 2006;19(10):1295-1301. 94. Zarate YA, Hopkin RJ. Fabry’s disease. Lancet. 2008;372(9647):1427-1435. 95. Altarescu G, Moore DF, Schiffmann R. Effect of genetic modifiers on cerebral lesions in Fabry disease.Neurology . 2005;64(12):2148-2150. 96. Banikazemi M, Desnick RJ, Astrin KH. Fabry disease. eMedicine Web Site. http://emedicine.medscape.com/article/951451- print. Updated July 8, 2009. Accessed July 30, 2009. 97. Nakao S, Takenaka T, Maeda M, et al. An atypical variant of Fabry’s disease in men with left ventricular hypertrophy. N Engl J Med. 1995;333(5):288-293.

31 98. Yoshitama T, Nakao S, Takenaka T, et al. Molecular genetic, biochemical, and clinical studies in three families wtih cardiac Fabry’s disease. Am J Cardiol. 2001;87(1):71-75. 99. Deegan PB, Bähner F, Barba M, Hughes DA, Beck M. Fabry disease in females: clinical characteristics and effects of enzyme replacement therapy. In: Mehta A, Beck M, Sunder-Plassman G, eds. Fabry Disease. Oxford, UK: Oxford PharmaGenesis; 2006. 100. Sims K, Politei J, Banikazemi M, Lee P. Stroke in Fabry disease frequently occurs before diagnosis and in the absence of other clinical events: natural history data from the Fabry Registry. Stroke. 2009;40(3):788-794. 101. Wilcox WR, Oliveira JP, Hopkin RJ, et al. Females with Fabry disease frequently have major organ involvement: lessons from the Fabry Registry. Mol Genet Metab. 2008;93(2):112-128. 102. Moore DF, Kaneski CR, Askari H, Schiffmann R. The cerebral vasculopathy of Fabry disease. J Neurol Sci. 2007;257(1-2):258- 263. 103. Schiffmann R. Fabry disease. Pharmacol Ther. 2009;122(1):65-77. 104. MacDermot KD, Holmes A, Miners AH. Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 60 obligate carrier females. J Med Genet. 2001;38(11):769-775. 105. Mitsias P, Levine SR. Cerebrovascular complications of Fabry’s disease. Ann Neurol. 1996;40(1):8-17. 106. Seino Y, Vyden JK, Philippart M, Rose HB, Nagasawa K. Peripheral hemodynamics in patients with Fabry’s disease. Am Heart J. 1983;105(5):783-787. 107. Sodi A, Ioannidis AS, Mehta A, Davey C, Beck M, Pitz S. Ocular manifestations of Fabry’s disease: data from the Fabry Outcome Survey. Br J Ophthalmol. 2007;91(2):210-214. 108. Branton MH, Schiffmann R, Sabnis SG, et al. Natural history of Fabry renal disease: influence of alpha-galactosidase A activity and genetic mutations on clinical course. Medicine (Baltimore). 2002;81(2):122-138. 109. Ortiz A, Oliveira JP, Waldeck S, Warnock DG, Cianciaruso B, Wanner C. Nephropathy in males and females with Fabry disease: cross-sectional description of patients before treatment with enzyme replacement therapy. Nephrol Dial Transplant. 2008;23(5):1600-1607. 110. Kampmann C, Baehner F, Whybra C, et al. Cardiac manifestations of Anderson-Fabry disease in heterozygous females. J Am Coll Cardiol. 2002;40(9):1668-1674. 111. Ramaswami U, Whybra C, Parini R, et al. Clinical manifestations of Fabry disease in children: data from the Fabry Outcome Survey. Acta Paediatr. 2006;95(1):86-92. 112. Cox-Brinkman J, Vedder A, Hollak C, et al. Three-dimensional face shape in Fabry disease. Eur J Hum Genet. 2007;15(5):535-542. 113. Moore DF, Ye F, Schiffmann R, Butman JA. Increased signal intensity in the pulvinar on T1-weighted images: a pathognomonic MR imaging sign of Fabry disease. AJNR Am J Neuroradiol. 2003;24(6):1096-1101. 114. Burlina AP, Manara R, Caillaud C, et al. The pulvinar sign: frequency and clinical correlations in Fabry disease. J Neurol. 2008;255(5):738-744. 115. Olivova P, van der Veen K, Cullen E, et al. Effect of sample collection on alpha-galactosidase A enzyme activity measurements in dried blood spots on filter paper. Clin Chim Acta. 2009;403(1-2):159-162. 116. Hoffmann B, Mayatepek E. Fabry disease--often seen, rarely diagnosed. Dtsch Arztebl Int. 2009;106(26):440-447. 117. Bennett RL, Hart KA, O’Rourke E, et al. Fabry disease in genetic counseling practice: recommendations of the National Society of Genetic Counselors. J Genet Couns. 2002;11(2):121-146. 118. OMIM #603903 Sickle cell anemia. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/ omim/603903. Accessed May 27, 2010. 119. Prengler M, Pavlakis SG, Prohovnik I, Adams RJ. Sickle cell disease: the neurological complications. Ann Neurol. 2002;51(5):543-552. 120. Taher A, Inati A, Kazzi ZN. Sickle cell anemia. eMedicine Web Site. http://emedicine.medscape.com/article/778971- overview. Updated May 6, 2010. Accessed May 27, 2010. 121. Steinberg MH. Pathophysiologically based drug treatment of sickle cell disease. Trends Pharmacol Sci. 2006;27(4):204-210. 122. Moritani T, Numaguchi Y, Lemer NB, et al. Sickle cell cerebrovascular disease: usual and unusual findings on MR imaging and MR angiography. Clin Imaging. 2004;28(3):173-186.

32 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

123. Earley CJ, Kittner SJ, Feeser BR, et al. Stroke in children and sickle-cell disease. Baltimore-Washington Cooperative Young Stroke Study. Neurology. 1998;51(1):169-176. 124. Clark BE, Thein SL. Molecular diagnosis of haemoglobin disorders. Clin Lab Haematol. 2004;26(3):159-176. 125. Adams R, McKie V, Nichols F, et al. The use of transcranial ultrasonography to predict stroke in sickle cell disease. N Engl J Med. 1992;326(9):605-610. 126. OMIM #154700 Marfan syndrome; MFS. National Center for Biotechnology Information Web site. http://www.ncbi.nlm. nih.gov/omim/154700. Accessed May 27, 2010. 127. Boileau C, Jondeau G, Mizuguchi T, Matsumoto N. Molecular genetics of Marfan syndrome. Curr Opin Cardiol. 2005;20(3):194-200. 128. Chen H. Marfan syndrome. eMedicine Web site. http://emedicine.medscape.com/article/946315-print. Updated March 2, 2010. Accessed May 27, 2010. 129. Wityk RJ, Zanferrari C, Oppenheimer S. Neurovascular complications of Marfan syndrome: a retrospective, hospital-based study. Stroke. 2002;33(3):680-684. 130. De Paepe A, Devereux RB, Dietz HC, Hennekam RCM, Pyeritz RE. Revised diagnostic criteria for the Marfan syndrome. Am J Med Genet. 1996;62(4):417-426. 131. Molecular testing. National Marfan Foundation Web site. http://www.marfan.org/marfan/2550/Molecular-Testing. Accessed December 10, 2009. 132. OMIM #162200 Neurofibromatosis, type 1; NF1. National Center for Biotechnology Information Web site. http://www. ncbi.nlm.nih.gov/omim/162200. Accessed May 27, 2010. 133. Rasmussen SA, Friedman JM. NF1 gene and neurofibromatosis 1.Am J Epidemiol. 2000;151(1):33-40. 134. Castle B, Baser ME, Huson SM, Cooper DN, Upadhyaya M. Evaluation of genotype-phenotype correlations in neurofibromatosis type 1. J Med Genet. 2003;40(10):e109. 135. Pletcher BA. Neurofibromatosis, type 1. eMedicine Web site. http://emedicine.medscape.com/article/1177266-print. Updated December 3, 2009. Accessed December 10, 2009. 136. Friedman JM, Arbiser J, Epstein JA, et al. Cardiovascular disease in neurofibromatosis 1: report of the NF1 Cardiovascular Task Force. Genet Med. 2002;4(3):105-111. 137. Rosser TL, Vezina G, Packer RJ. Cerebrovascular abnormalities in a population of children with neurofibromatosis type 1. Neurology. 2005;64(3):553-555. 138. OMIM #540000 Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes; MELAS. National Center for Biotechnology Information Web site. http://www.ncbi.nlm.nih.gov/omim/540000. Accessed May 27, 2010. 139. Goto Y, Nonaka I, Horai S. A mutation in the tRNA(Leu)(UUR) gene associated with the MELAS subgroup of mitochondrial encephalomyopathies. Nature. 1990;348(6302):651-653. 140. Scaglia F. MELAS syndrome. eMedicine Web site: http://emedicine.medscape.com/article/946864-print. Updated July 23, 2009. Accessed December 11, 2009. 141. Sproule DM, Kaufmann P. Mitochondrial encephalopathy, lactic acidosis, and strokelike episodes: basic concepts, clinical phenotype, and therapeutic management of MELAS syndrome. Ann NY Acad Sci. 2008;1142:133-158. 142. Kim I-O, Kim JH, Kim WS, Hwang YS, Yeon KM, Han MC. Mitochondrial myopathy-encephalopathy--lactic acidosis--and strokelike episodes (MELAS) syndrome: CT and MR findings in seven children.AJR Am J Roentgenol. 1996;166(3):641-645. 143. OMIM *120130 Collagen, type IV, alpha-1; COL4A1. National Center for Biotechnology Information Web site. http://www. ncbi.nlm.nih.gov/omim/120130. Accessed May 3, 2010. 144. Mine M, Tournier-Lasserve E. Intracerebral hemorrhage and COL4A1 mutations from preterm infants to adult patients. Ann Neurol. 2009;65(1):1-2. 145. Gould DB, Phalan FC, Breedveld GJ, et al. Mutations in COL4A1 cause perinatal cerebral hemorrhage and porencephaly. Science. 2005;308(5725):1167-1171. 146. van der Knaap MS, Smit LME, Barkhof F, et al. Neonatal porencephaly and adult stroke related to mutations in collagen IV A1. Ann Neurol. 2006;59(3):504-511. 147. Sibon I, Coupry I, Menegon P, et al. COL4A1 mutation in Axenfeld-Rieger anomaly with leukoencephalopathy and stroke. Ann Neurol. 2007;62(2):177-184.

33 148. Plaisier E, Gribouval O, Alamowitch S, et al. COL4A1 mutations and hereditary angiopathy, nephropathy, aneurysms, and muscle cramps. N Engl J Med. 2007;357(26):2687-2695. 149. Vahedi K, Massin P, Guichard JP, et al. Hereditary infantile hemiparesis, retinal arteriolar tortuosity, and leukoencephalopathy. Neurology. 2003;60(1):57-63. 150. Shah S, Kumar Y, McLean B, et al. A dominantly inherited mutation in collagen IV A1 (COL4A1) causing childhood onset stroke without porencephaly. Eur J Paediatr Neurol. 2010;14(2):182-187. 151. Rosendorff A, Dorfman DM. Activated protein C resistance and factor V Leiden. Arch Pathol Lab Med. 2007;131(6):866-871. 152. Varga EA, Moll S. Prothrombin 20210 mutation (factor II mutation). Circulation. 2004;110(3):e15-e18. 153. Goldenberg NA, Manco-Johnson MJ. Protein C deficiency.Haemophilia . 2008;14(6):1214-1221. 154. Mustafa S, Pabinger I, Mannhalter C. Protein S deficiency type I: identification of point mutations in 9 of 10 families. Blood. 1995;86(9):3444-3451. 155. Picard V, Nowak-Göttl U, Biron-Andreani C, et al. Molecular bases of antithrombin deficiency: twenty-two novel mutations in the antithrombin gene. Hum Mutat. 2006;27(6):600. 156. Lesnick Oberstein SAJ, Boon EMJ, Dichgans M. Gene reviews: CADASIL. NCBI Bookshelf Web site. http://www.ncbi.nlm.nih. gov/bookshelf/br.fcgi?book=gene&part=. Published March 15, 2000. Updated July 23, 2009. Accessed May 27, 2010. 157. del Río-Espínola A, Mendióros M, Domingues-Montanari S, et al. CADASIL management or what to do when there is little one can do. Expert Rev Neurother. 2009;9(2):197-210. 158. Cunha L. Marfan’s syndrome. In: Caplan LR, Bogousslavsky J, eds. Uncommon Causes of Stroke. 2nd ed. Cambridge, UK: Cambridge University Press; 2008:131-134. 159. Nedeltchev K, Mattle HP. Cerebrovascular manifestations of neurofibromatosis. In: Caplan LR, Bogousslavsky J, eds. Uncommon Causes of Stroke. 2nd ed. Cambridge, UK: Cambridge University Press; 2008:221-224. 160. Tietjen GE. The risk of stroke in patients with migraine and implications for migraine management. CNS Drugs. 2005;19(8):683-692. 161. Schürks M, Diener H-C, Goadsby P. Update on the prophylaxis of migraine. Curr Treat Options Neurol. 2008;10(1):20-29. 162. Chabriat H, Bousser MG. Cerebral autosomal dominant ateriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). In: Caplan LR, Bogousslavsky J, eds. Uncommon Causes of Stroke. 2nd ed. Cambridge, UK: Cambridge University Press; 2008:115-121. 163. Gould DB, Phalan FC, van Mil SE, et al. Role of COL4A1 in small-vessel disease and hemorrhagic stroke. N Engl J Med. 2006;354(14):1489-1496. 164. Isono M, Ishii K, Kamida T, Inoue R, Fujiki M, Kobayashi H. Long-term outcomes of pediatric moyamoya disease treated by encephalo-duro-arterio-synangiosis. Pediatr Neurosurg. 2002;36(1):14-21. 165. Kim D-S, Kang S-G, Yoo D-S, Huh P-W, Cho KS, Park CK. Surgical results in pediatric moyamoya disease angiographic revascularization and the clinical results. Clin Neurol Neurosurg. 2007;109(2):125-131. 166. Kuroda S, Houkin K. Moyamoya disease: current concepts and future perspectives. Lancet Neurol. 2008;7(11):1056-1066. 167. Sakamoto H, Kitano S, Yasui T, et al. Direct extracranial-intracranial bypass for children with moyamoya disease. Clin Neurol Neurosurg. 1997;99(suppl 2):S128-S133. 168. Koga Y, Akita Y, Junko N, et al. Endothelial dysfunction in MELAS improved by l-arginine supplementation. Neurology. 2006;66(11):1766-1769. 169. Eng CM, Guffon N, Wilcox WR, et al. Safety and efficacy of recombinant human alpha-galactosidase A--replacement therapy in Fabry’s disease. N Engl J Med. 2001;345(1):9-16. 170. Replagal [summary of product characteristics]. Hampshire, UK: Shire Human Genetic Therapies; 2009. 171. Fabrazyme [package insert]. Cambridge, MA: Genzyme Corporation; 2009. 172. Kalliokoski RJ, Kantola I, Kalliokoski KK, et al. The effect of 12-month enzyme replacement therapy on myocardial perfusion in patients with Fabry disease. J Inherit Metab Dis. 2006;29(1):112-118. 173. Eng CM, Germain DP, Banikazemi M, et al. Fabry disease: guidelines for the evaluation and management of multi-organ system involvement. Genet Med. 2006;8(9):539-548. 174. Adams RJ. Stroke prevention and treatment in sickle cell disease. Arch Neurol. 2001;58(4):565-568.

34 New Insights Into the Diagnosis and Treatment of Single-Gene Disorders Associated With Cryptogenic Ischemic Stroke

175. Walters MC, Storb R, Patience M, et al. Impact of bone marrow transplantation for symptomatic sickle cell disease: an interim report. Blood. 2000;95(6):1918-1924. 176. Adams RJ, Mckie VC, Hsu L, et al. Prevention of a first stroke by transfusions in children with sickle cell anemia and abnormal results on transcranial Doppler ultrasonography. N Engl J Med. 1998;339(1):5-11. 177. Swerdlow PS. Red cell exchange in sickle cell disease. Hematology Am Soc Hematol Educ Program. 2006:48-53. 178. Steinberg MH, Lu Z-H, Barton FB, Terrin ML, Charache S, Dover GJ. Fetal hemoglobin in sickle cell anemia: determinants of response to hydroxyurea. Blood. 1997;89(3):1078-1088. 179. Ballas SK, Marcolina MJ, Dover GJ, Barton FB. Erythropoietic activity in patients with sickle cell anaemia before and after treatment with hydroxyurea. Br J Haematol. 1999;105(2):491-496. 180. Kratovil T, Bulas D, Driscoll MC, Speller-Brown B, McCarter R, Minniti CP. Hydroxyurea therapy lowers TCD velocities in children with sickle cell disease. Pediatr Blood Cancer. 2006;47(7):894-900. 181. Zimmerman SA, Schultz WH, Burgett S, Mortier NA, Ware RE. Hydroxyurea therapy lowers transcranial Doppler flow velocities in children with sickle cell anemia. Blood. 2007;110(3):1043-1047. 182. Lefèvre N, Dufour D, Gulbis B, Lê PQ, Heijmans C, Ferster A. Use of hydroxyurea in prevention of stroke in children with sickle cell disease. Blood. 2008;111(2):963-964. 183. Hankins J, Aygun B. Pharmacotherapy in sickle cell disease -- state of the art and future prospects. Br J Haematol. 2009;145(3):296-308. 184. Lancaster JR Jr. Sickle cell disease: loss of the blood’s WD40? Trends Pharmacol Sci. 2003;24(8):389-391.

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