Porphyrias – an Overview and Update for Physicians and Their Staffs

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Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs

Porphyrias – An Overview and Update for Physicians and their Staffs

Authors: Abstract Brandon Marion, MD Heme is an essential molecule involved in various biochemical processes in many species. It is used in the formation of cytochromes P- Jared Rejeski, MD 450, mitochondrial cytochromes, hemoproteins, catalase, peroxidase, Sean Rudnick, MD myoglobin, and hemoglobin. Formation of the heme molecule involves a multistep process using eight enzymes. Biosynthesis of heme occurs Herbert L. Bonkovsky, MD in the mitochondria and in the cytoplasm. Most tissues in the human body synthesize heme, but the main sites of formation are in the bone marrow (erythroblasts) and in the liver (hepatocytes). Porphyrias are a Affiliation: unique group of disorders mainly due to inborn errors of metabolism of Section on Gastroenterology the heme synthetic pathway. The deficient activity of the enzymes can and Hepatology, Department lead to a build-up of heme precursors, resulting in wide heterogeneity of of Internal Medicine, clinical symptoms. To date, there are nine described porphyrias: aminolevulinic acid dehydratase deficient porphyria (ALADP), acute Wake Forest University intermittent porphyria (AIP), hereditary coproporphyria (HCP), School of Medicine, variegate porphyria (VP), porphyria cutanea tarda (PCT), Winston-Salem, NC, 27157 hepatoerythropoietic porphyria (HEP), congenital erythropoietic porphyria (CEP), erythropoietic protoporphyria (EPP), and X-linked protoporphyria (XLPP). The classification of porphyrias is based on Email Addresses: 1) the main sites of heme precursor synthesis (hepatic, erythropoietic), [email protected] 2) acute or chronic porphyria, and 3) cutaneous involvement. In this review, we focus on AIP, PCT, and EPP, the three most common forms [email protected] of porphyria in the United States. A case vignette for each of the three is [email protected] provided and followed by a discussion regarding the clinical features, pathogenesis, diagnosis/management, and prognosis of each. [email protected] Management of AIP currently revolves around avoidance of drugs and chemicals and severe caloric deprivation, which may trigger acute Address for attacks, and use of intravenous heme for acute attacks. Exciting new Correspondence: therapies, particularly siRNA to down regulate hepatic 5-aminolevulinic acid synthase, are under active development. Management of EPP Herbert L. Bonkovsky, MD currently involves protection from sunlight, but implants of afamelanotide have shown good efficacy and are already approved by NRC E-112, Wake Forest the European Medicines Agency. Baptist Medical Center, 1 Medical Center Blvd, Abbreviations used: AFP – alpha-fetoprotein, AIP – acute Winston-Salem, NC, 27157 intermittent porphyria, ALA – 5 [delta]-aminolevulinic acid, ALADP – aminolevulinic acid dehydratase deficient porphyria, ALAS-1 – 5- Key words: 5 [delta]- aminolevulinic acid synthase-1, CEP – congenital erythropoietic aminolevulinic acid, 5- porphyria, CT – computed tomography, ePP – erythrocyte aminolevulinic acid protoporphyrin, EPP – erythropoietic protoporphyria, GABA – gamma- amino butyric acid, HCC – Hepato-cellular carcinoma, HCP – synthase, heme, hepatitis C, hereditary coproporphyria, HCV – hepatitis C virus, HEP – iron, photosensitivity, hepatoerythropoietic porphyria, HFE – the gene mutated in the porphobilinogen, porphyria, common, HLA-linked form of hereditary hemochromatosis, HIV – porphyrins human immunodeficiency virus, PBG – porphobilinogen, PBGD – porphobilinogen deaminase, PCT – porphyria cutanea tarda, PP – protoporphyrin, UROD - uroporphyrinogen decarboxylase, VP – variegate porphyria, XLPP – X-linked protoporphyria

1. Introduction: Overview of the disease that has been prevalent in both Porphyrias history books and folklore. It is believed Defects within the eight step process that the first mention of porphyria was by of heme synthesis result in the disabling Hippocrates in 460 BCE and some believe that King George III and Vincent van Gogh effects of porphyria (Figure 1). The [1-5] symptoms associated with the porphyrias are may have suffered from porphyria. This wide-ranging and often result in broad review will focus on the three most common evaluations before a diagnosis is considered types of porphyria seen in the United States (US): acute intermittent porphyria (AIP), and confirmed. There are two broad categories of classification for the eight porphyria cutanea tarda (PCT), and porphyrias: hepatic or erythropoietic and erythropoietic protoporphyria (EPP). acute or chronic (Table 1). Porphyria is a

Table 1. Main Schemes of Classification of the Porphyrias Acute Hepatic porphyrias Chronic Hepatic Erythropoietic porphyrias porphyrias Types of 1. Aminolevulinic acid dehydratase 1. Porphyria cutanea tarda 1. Congenital porphyria deficient porphyria 2. Hepatoerythropoietic erythropoietic porphyria 2. Acute intermittent porphyria porphyria 2. Erythropoietic 3. Hereditary coproporphyria protoporphyria 4. Variegate porphyria 3. X-linked protoporphyria Gender Female > male [~4>1] Male > female Frequency Site of origin Liver Liver Bone marrow Inheritance Autosomal dominant – AIP, HCP, Usually acquired. Autosomal recessive – EPP VP Autosomal recessive or co- X-linked-XLPP ALADP - autosomal recessive dominant Autosomal recessive – CEP Key clinical Neurovisceral symptoms CEP-- Cutaneous lesions on features Cutaneous lesions on sun sun exposed areas (painless Photocutaneous disease in HCP, VP exposed areas, especially blisters, skin fragility, after minor mechanical sclerodermatous changes, trauma (painless blisters, hypertrichosis) skin fragility, EPP, XLPP—Acute sclerodermatous changes,. Burning, pain, pruritus, Cheeks and temples-- swelling after sun exposure hypertrichosis Key ALADP—Increased urinary ALA, Increased urinary Uro and CEP—increased urinary biochemical CP 3 heptacarboxyl- porphyrins, uroporphyrin 1, findings in AIP, HCP, VP—Increased urinary Increased stool coproporphyrin 1, active ALA, PBG, uroporphyrin 1, CP 3 isocoproporphyrins EPP, XLPP—Urine is disease normal unless hepatopathy has developed. Increased PP in plasma and RBCs Abbreviations: AIP, Acute intermittent porphyria; ALA, 5-aminolevulinic acid; CEP, congenital erythropoietic porphyria; CP, coproporphyrin; EPP, erythropoietic protoporphyria; HCP, hereditary coproporphyria; PBG, porphobilinogen; VP, variegate porphyria.

Figure 1. Summary of the heme synthetic pathway, highlighting enzymatic defects associated with the porphyrias.

Figure 1. The heme synthetic pathway involves eight enzymes, four of which are active in the mitochondria, and four of which are active in the cytoplasm. The pathway is initiated and completed in the mitochondria. Intermediate steps in the cytoplasm begin with the activity of 5-aminolevulinic acid [ALA] dehydratase, also known as PBG synthase. Open arrows indicate progression through the pathway. Deficiency [indicated by blocked red arrows] in any of the eight enzymes involved in the pathway may contribute to development of acute or chronic hepatic porphyrias or erythropoietic porphyrias, as shown in red. Abbreviations: Ac, acetate; AIP, acute intermittent porphyria; ALA, 5-aminolevulinic acid; ALADP, ALA dehydratase deficiency porphyria; CEP, congenital erythropoietic porphyria; copro’gen, coproporphyrinogen; EPP, erythropoietic protoporphyria; HCP, hereditary coproporphyria; HEP, hepatoreythropoietic porphyria; PBG, porphobilinogen; PCT, porphyria cutanea tarda; Pr, propionate; proto’gen, protoporphyrinogen; Uro’gen, uroporphyrinogen; Vi, vinyl; VP, variegate porphyria. (Used with permission from Lane AM, McKay JT, Bonkovsky HL. Advances in the management of erythropoietic protoporphyria - role of afamelanotide. Appl Clin Genet. 2016; 9:179-189.)

2. The acute porphyrias – acute was normal including liver function tests, intermittent porphyria as the paradigm serum lipase and amylase, and a serum Helicobacter pylori antibody. In addition, a 2.1. Case Vignette contrast-enhanced computed tomography A 26-year-old woman, G0P0, with (CT) scan of the abdomen and pelvis was history of anxiety presented to the obtained and normal, as had three previous emergency room with severe, colicky lower CT scans. abdominal pain that had been present in gradually ascending severity for the past 18 After receiving intravenous fluids and hours. Her abdominal pain, as before, was analgesics, she had improvement in her gradual in onset and did not improve with symptoms. Just prior to her discharge, she over the counter acetaminophen or was witnessed by the emergency room staff naproxen. In addition to her abdominal pain, to have a grand-mal seizure, and she was she also had noted fatigue, weakness, and administered intravenous lorazepam. difficulty with concentration for several She was admitted for additional days. She previously had presented twice to observation. Given her young age, a local emergency room with similar abdominal pain, hyponatremia, and seizure, symptoms over the past six months. a spot urinary porphobilinogen (PBG) and 5- On review, she has been actively [delta]-aminolevulinic acid (ALA) were attempting to lose weight. She has been on a checked and were found to be markedly vigorous exercise and weight loss regimen elevated. Acute intermittent porphyria was over the past 5 months. She has not been suspected at this point. A 24-hour urine PBG prescribed any new medications. Currently, was significantly elevated at 111 mg/d she is taking an oral contraceptive, which (reference range 0-4). She was administered intravenous hematin at 4 mg/kg/d for 4 days she has been taking for 3 years. She has a surgical history of an appendectomy 8 years with improvement in her symptoms and was ago. She has also been recently referred to discharged in stable condition. her local general surgeon for consideration 2.2. Clinical Features of a cholecystectomy because of her recurrent abdominal pain. She notes that, The term “acute porphyria” was first during episodes of recurrent pain, she coined by the Swedish internist Jan develops nausea, anorexia, darkening of Waldenström to describe Swedish patients [6] urine color and constipation. who had episodic neurologic crises. The acute porphyrias can present with In the emergency room, height was 67 nonspecific symptoms. Patients who inches; weight 175 lbs, BMI 27.4 kg/m2; experience symptoms due to acute temperature was 98.6 F, blood pressure intermittent porphyria are often 152/84 mmHg, heart rate 107 beats/min, misdiagnosed and dismissed as having respiratory rate 18 breaths/min. She was functional or psychosomatic pain. Some oriented but lethargic and slow to respond to patients are also labeled as drug seekers questions. The cardiopulmonary exam was given recurrent presentations for pain normal. The abdomen was soft, without a satisfactory response to nondistended, and nontender to palpation analgesics.[7] with hypoactive bowel sounds. A neurological exam revealed no focal deficits. The acute hepatic porphyrias include aminolevulinic acid dehydratase deficient The laboratory evaluation revealed porphyria (ALADP), acute intermittent hyponatremia, with serum sodium = 128 porphyria (AIP), hereditary coproporphyria mEq/L. Her remaining laboratory evaluation

(HCP), and variegate porphyria (VP). The system. Peripheral neuropathy is a mostly clinical characteristics of an acute porphyric motor neuron process due to axonal attack are similar for each of the acute degeneration.[15] Patients who have frequent porphyrias, but are typically more severe in acute attacks can develop chronic AIP.[8] It is thought that the buildup of heme neuropathic pain.[16] Patients can even precursors, especially of ALA, has effects on develop respiratory failure and the nervous system, which causes most of quadriparesis. When the central nervous the clinical symptoms. The acute attack, as system is involved, patients can present with in the foregoing clinical vignette, typically is irritability, insomnia, anxiety, paranoia, characterized by severe abdominal pain, hallucinations, and psychoses.[9] Major neurovisceral disturbances, and circulatory motor seizures occur in up to 20% of acute disturbances.[9] porphyric attacks.[17] Treatment with Except for the very rare autosomal anticonvulsants can be challenging as many of the commonly used anti-convulsants recessive ALADP form, it is atypical for persons with acute porphyrias to experience (barbiturates, hydantoins, valproate, etc) can symptoms before the onset of puberty. Acute precipitate and/or worsen acute porphyric attacks are more common and severe in attacks. women than in men (ratio ~ 4:1). Acute In addition to the psychiatric attacks occur in women with peak incidence symptoms, schizophrenia and bipolar in the third and fourth decades of life.[9,10] It disorder have been associated with AIP. is less likely for women to experience acute Waldenström observed that schizophrenia attacks before menarche or after menopause. was common in families of patients with Medications, especially inducers of AIP.[31] In 1993, Sanders et al described an cytochromes P-450 and hepatic ALA association between genetic variations of the synthase, and suicide substrates of porphobilinogen deaminase gene and cytochromes P-450, are major triggering or schizophrenia.[32] Several studies after this exacerbating factors. Others include have not been able to reproduce these progesterone and related chemicals, oral findings however. Results from a Swedish contraceptives, caloric deprivation, fasting, study showed that individuals with AIP had severe illness, and crash diets.[9,11,12] a fourfold excess risk of being diagnosed [33] Abdominal pain is regarded as a with schizophrenia or bipolar disorder. hallmark of an acute porphyric attack as it This study also showed an increased risk of occurs in 85-90% of patients with AIP.[13,14] schizophrenia and bipolar disorder in first It is thought to be due to autonomic nervous degree relatives of individuals with AIP. system dysfunction. Patients can also have 2.3. Pathogenesis symptoms of nausea, vomiting, and constipation with abdominal imaging Porphyrias are caused by defects in revealing a paralytic ileus.[9] Bowel sounds genes of heme biosynthesis (Figure 1). are often found to be decreased or absent on These genetic disorders lead to high physical exam. Fever, diaphoresis, accumulations and toxic buildup of tachycardia, and systemic arterial porphyrins and their precursors, ALA and hypertension, yet also with orthostatic PBG, which, respectively, can cause hypotension, may also be present. These are dermatologic and neurovisceral symptoms. evidence of sympathetic nervous system These inborn errors of metabolism can lead hyperactivity. to hepatic overproduction of the porphyrin precursors, ALA and PBG. The acute porphyrias also exhibit effects on the central and peripheral nervous

As already described, medications, supplies hepatic heme to maintain normal fasting, and progesterone are among functional status. When cytochrome P-450 precipitating factors of the acute enzymes are induced by certain medications porphyrias.[18,19] There has been much or chemicals, the demand for heme is interest regarding the pathogenesis of increased. This, in turn, leads to depression symptoms due to porphyria. Bonkovsky and of hepatic ALAS-1 and to uncontrolled Schady and others postulated two overproduction of ALA and, except for hypotheses regarding this: 1) cellular heme ALADP, also PBG. Additionally, it has been deficiency causing a significant reduction in observed that certain medications/drugs can heme-proteins in neuronal cells and 2) ALA also directly activate ALAS-1. This being neurotoxic at the levels seen during an ultimately results in a buildup of the heme acute porphyria attack.[29] The causative precursors ALA and PBG due to the factors are thought to increase the demand deficiency of PBGD. for hepatic heme. The decreased hepatic ALA, PBG, and other hepatic heme heme induces the synthesis of the precursors are thought to be able to cross the housekeeping form of 5-aminolevulinic acid blood brain barrier.[9] Once this occurs, the synthase (ALAS-1). This enzyme is known heme precursors exert their neurotoxic as the gateway for the biosynthesis of heme effects throughout the brain. ALA is also as it is not only the first enzyme in the structurally similar to gamma-amino butyric pathway, but it is also normally the rate- acid (GABA). Thus, it is believed that ALA limiting step in synthesis. has neurotoxic effects in the brain and also In AIP, the major metabolic defect is has the potential to bind to GABA receptors. decreased activity (usually about 50% of Neurological symptoms such as mental normal) of hepatic PBG deaminase (PBGD), status change and seizures are felt to be also known as hydroxymethyl bilane secondary to this mechanism. In all acute synthase. The inheritance is usually porphyrias, there are elevations in plasma autosomal dominant, albeit with low clinical and urine ALA levels, which reinforces the penetrance, due to several gene mutations.[9] notion that it is a major pathogenic factor. PBGD is the third enzyme in the heme pathway, following ALA synthase and then 2.4. Management ALA dehydratase (Figure 1). When precipitating factors are avoided, the reduced See Table 2. enzyme activity of PBGD adequately

Table 2. Summary of Management of the Acute Porphyrias

Recommendations Dietary/Lifestyle - Avoidance of prolonged fasting states, crash diets modifications - Avoidance of alcohol or minimal use - Diet balanced in carbohydrates (30-40 kcal/kg IBW/d) and protein (1-1.5 g/kg IBW/d) - Minimize excessive emotional stress, physical exertion - Identify precipitating agents and avoid known triggers Laboratory evaluation - Urinary ALA, PBG, porphyrins (markedly elevated during an acute attack) – spot urine sample [26] - Plasma and fecal porphyrins

- Erythrocyte PBG deaminase level - Genetic testing/gene sequencing (if positive biochemical evaluation) - Monitor iron/ferritin levels - Electrolytes, renal/hepatic function Acute porphyria - Goal is to reduce hepatic ALAS-1 activity attacks - > 300 g carbohydrate per day (enterally or parenterally) - Intravenous hydration with 10% glucose solution daily - Analgesics: acetaminophen, meperidine, morphine - Intravenous heme 3-5 mg/kg daily for 3-5 days - Propranolol or nadolol (sympathetic hyperactivity) - Monitor urinary ALA, PBG Hepatocellular - Age > 50 carcinoma screening - Abdominal ultrasound (or alternative form of imaging) every 6-12 months - Serum AFP every 6-12 months Special considerations - GnRH analogue, e.g., Leuprolide - Low dose oral contraceptives Cyclical attacks - - Clonazepam, magnesium, gabapentin, levetiracetam have associated with been shown to be tolerated menstruation - Seizures Frequent or refractory - Consider referral for liver transplantation acute attacks AFP – alpha-fetoprotein, ALA – 5- [delta]-aminolevulinic acid, g/kg – grams per kilogram, IBW/d – ideal body weight per day, mg/kg – milligrams per kilogram, PBG – porphobilinogen, ALAS-1 - 5-aminolevulinic acid synthase-1

2.1. Prognosis chronic tubulointerstitial nephropathy and [12,21] Acute porphyric attacks can last days focal cortical atrophy. There have also to weeks. When managed adequately, been studies that suggest chronic kidney symptoms typically improve in three to five disease may be due to porphyria-associated nephropathy. This nephropathy is believed days. During the interim between acute attacks, patients are mostly asymptomatic. to be more likely to occur in patients who Recurrent attacks can result in neuropathy harbor a hypomorphic genetic variant in the human peptide transporter 2, which is a and neurological deficits like wrist and foot [22,23] drop.[16] However, motor symptoms are not transporter of ALA. The hypothesis is always permanent and can resolve slowly that more nephrotoxic ALA accumulates in over a period of months to years. those with the hypomorphic allele. Studies of individuals with long- Patients with biochemically active standing disease have revealed an increased acute hepatic porphyria are also at increased risk of developing hepatic fibrosis, which prevalence of chronic kidney and liver [24] disease.[20,21] The development of kidney may progress to develop cirrhosis. It is disease has been found to be secondary to established that this cohort is at an increased risk of developing hepatocellular carcinoma

Copyright 2017 KEI Journals. All Rights Reserved Page │7 Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs with a higher incidence between the ages of raising the awareness of diagnostic 50-60 years old.[25,26] Screening for evaluation and management of the acute hepatocellular carcinoma (HCC) with hepatic porphyrias. abdominal imaging and serum alpha- fetoprotein (AFP) levels are recommended 3. Porphyria cutanea tarda in individuals age 50 or older, especially in those with frequent attacks or long standing 3.1. Case Vignette biochemically active disease. A 57-year-old male with a family Novel therapies for acute porphyria are history including hemochromatosis and currently being developed. Gene therapy is cirrhosis in his father presented for one such alternative therapy. Currently, a evaluation of blisters and vesicles on his method for delivering PBGD to hepatocytes hands. He had seen several local physicians via a viral vector is being studied. At this who were unable to identify the etiology of time, this approach has not shown significant his skin lesions. The patient reported improvement in ALA or PBG levels.[27] smoking approximately 1/2 pack of Investigation of the use of small interfering cigarettes per day for approximately 20 RNA (siRNA) directed against ALAS-1 is years, and consuming up to a case of beer also underway. Givosiran (Alnylam per day for approximately 15 years. He also Pharmaceuticals, Cambridge, MA) is a formerly used intravenous drugs and siRNA designed to target hepatic ALAS-1, intranasal cocaine. Physical exam was which would lead to a reduction in ALA notable for scattered blisters, vesicles, and synthesis.[28] Preliminary studies have sores on the hands, and scalp. Some of the shown decreased expression of ALAS-1 areas had a crusted appearance, but there after a single subcutaneous injection.[29] were no signs of secondary infection. The Individuals with severe, refractory, or liver edge was firm and palpable under the recurrent attacks, despite optimal right costal margin. Complete blood count management, should be considered for was within normal limits. Liver chemistries orthotopic liver transplantation as this has showed mildly elevated serum been curative.[30] aminotransferase levels (AST 40, ALT 71) with normal total bilirubin and alkaline The quality of life in any disease state phosphatase. Serum ferritin was elevated at is important to assess. A small study in 516 ng/mL, and transferrin saturation was Spain evaluated anthropometric and quality- increased at 55%. A random spot urine of-life parameters in patients with AIP and revealed markedly increased urinary total showed statistically significant differences in porphyrins (2,250 mcg/g creatinine), with certain anthropometric measures and in the predominance of 8- and 7- [uro- and quality of life assessed by the EuroQol-5D [35] heptacarboxyl-] porphyrins. Plasma compared to controls. These tools have porphyrin was increased at 5 mcg/dL, also the potential to be included in the predominantly uro- and heptacarboxyl armamentarium of clinicians to help guide porphyrins, and the peak of fluorescence care for patients with acute intermittent emission was at 620 nm. These findings porphyria. established the diagnosis of PCT. Activity The greatest challenge currently still of uroporphyrinogen decarboxylase in remains in making a diagnosis of acute erythrocytes was normal, and genetic testing hepatic porphyria in patients presenting with of the uroporphyrinogen decarboxylase diverse features of acute attacks. Once (UROD) gene revealed no mutations, established, prevention of future acute indicating that the man had sporadic, attacks is key and much effort continues at acquired, type I PCT. Hepatitis C virus

(HCV) antibody was positive, and infection In most countries and regions, PCT is was confirmed with positive HCV RNA the most common type of porphyria in followed by HCV genotyping (1a). Genetic humans.[36] It is associated with iron loading testing for hemochromatosis (HFE) was in the liver and additional tissues. Iron notable for compound heterozygosity for overload is often related to a mutation in the C282Y (major) and H63D (minor) hereditary hemochromatosis genes (typically mutations. Fibroscan showed median HFE). Additional associations include stiffness of 8 kPa corresponding to a Metavir excess alcohol use (alcohol-related liver fibrosis score of F2/4. Liver biopsy disease), and cigarette use. Infections with confirmed F2 disease, and showed moderate chronic HCV or human immunodeficiency (2/4) iron staining, predominantly in virus (HIV) are also associated with PCT. periportal hepatocytes. The patient was Hepatic involvement is characterized by strongly advised to discontinue alcohol elevated aminotransferase levels in consumption and tobacco use. Therapeutic conjunction with elevated iron indices.[37] phlebotomy was initiated weekly until serum Markers of hepatic synthetic function are ferritin had dropped to goal range (25-75 generally normal at presentation. ng/mL), at which time HCV therapy with sofosbuvir/ledipasvir was initiated with 3.3. Pathogenesis regression of skin lesions and cure of HCV The primary metabolic defect driving infection. PCT did not recur during 2 years PCT is a deficiency in the activity of liver of follow-up after these therapies. UROD. This enzyme's role is to convert uroporphyrinogen to coproporphyrinogen 3.2. Clinical Features (Figure 1), which then goes on to form PCT, one of the chronic hepatic heme. Inhibition of this enzyme, whether porphyrias is clinically characterized first through acquired deficiency of activity, or and foremost by vesicles, bullae, blisters, hereditary partial deficiency, in the presence and sores in sun exposed areas, most notably of other risk factors, may result in the hands. This does not represent acute accumulation of uro- and heptacarboxyl- photosensitivity, as is seen in EPP/X-linked porphyrins within hepatocytes. The major protoporphyria (XLPP), but rather results additional factors which diminish the from mild trauma to sun exposed areas, activity of UROD include alcohol including forehead, ears, and neck. In excess/alcohol-related liver disease, contrast to acute porphyrias, there are no exposure to estrogens, chronic infection with acute neurovisceral attacks, and the HCV or HIV, and iron overload (usually cutaneous manifestations are insidious in related to HFE mutations).[38-45] A onset. With chronic and repeated trauma combination of these pathogenic factors is and ongoing sun exposure, chronic believed to induce oxidative stress within the thickening of the skin with sclerodermatous- liver leading to oxidation of uro- and like changes may develop, as may small heptacarboxyl-porphyrinogens to their whitish papules, called ‘milia.’ corresponding porphyrins which are not substrates for UROD (Figure 2).

Figure 2. The molecular pathogenesis of porphyria cutanea tarda.

Figure 2. The central roles of increased reactive oxygen species, iron, and HCV infection are highlighted. (From Caballes FR et al. Liv Intl 2012; 32: 880-93, used with permission of the authors and publisher.) 3.4. Diagnosis and Management at modifiable risk factors, such as avoidance Observation of the classic cutaneous of alcohol, cigarettes, and estrogens. manifestations as described above in Treatment of underlying infectious conjunction with associated risk factors, precipitants such as HCV and HIV should be should raise suspicion for PCT, and prompt pursued. further evaluation. The key diagnostic In the presence of iron overload, feature, is a marked increase in urinary therapeutic phlebotomy should commence porphyrins, with predominance of uro- and with an initial goal of serum ferritin of 25 - heptacarboxyl- porphyrins. A mild increase 75 ng/mL. The use of low doses of in urinary ALA and stool uroporphyrin and antimalarial drugs (chloroquine or isocoproporphyrins can also be observed. hydroxychloroquine, 100 mg initially twice Urinary PBG is normal.[46,47] or three times per week, with gradual Treatment of PCT involves avoidance increase to daily dosing over the first month) of sunlight and use of appropriate sunscreens can be utilized to increase removal of porphyrins from hepatocytes (Table 3).[48] and protection of sun-exposed skin to minor trauma. Additional interventions are aimed Remission of symptoms may take as long as six to nine months on therapy.

Table 3. Summary of Management of PCT Management/treatment Monitoring / Comments Behavioral  Avoid sunlight Most commercial sunscreen products of little or  Utilize appropriate no value because they do not block long UV- sunscreen / clothing blue light [Soret band]. Opaque zinc or titanium  Alcohol and oxide pastes are effective. tobacco cessation Protect especially the hands and forearms, face, neck Dietary -Avoid excess iron including:  Supplements  Red meats Iron removal -Therapeutic phlebotomy Target ferritin (marker of total body iron) 25-75  Weekly or ng/mL Biweekly (~500 mL/session) Particularly indicated in subjects with  Avoid anemia (no hemochromatosis. Volume of blood removed phlebotomy if Hgb may be modified if necessary—for example < 11 g/dL or Hct < small subjects may have only ~300 mL blood 33%) removed/ session. -Chelation therapy  Deferasirox (10 Chelation therapy more expensive and with mg/Kg/day) more frequent adverse effects, but may be  Adverse effects: indicated in those with anemia, such as in rash, hepatic/renal setting of ESRD. toxicity Antimalarials -Chloroquine (125 mg * As an adjunct twice/week) to iron removal  Can be used as Risk of relapse likely higher than after iron monotherapy if reduction therapy anemic -Hydroxychloroquine (200 mg twice/week) Antiviral -Hepatitis C therapy  Genotype - HCV RNA levels dependent Follow recommended guidelines of  Current DAA AASLD/IDSA regimens are well- tolerated AASLD, American Association for the Study of Liver Diseases; DAA, direct acting antivirals; ESRD, end-stage renal disease; HCV, hepatitis C; Hgb, hemoglobin; Hct, hematocrit; IDSA, Infectious Disease Society of America.

3.5. Prognosis 4. Erythropoietic Protoporphyria Although the long-term prognosis is and X-linked Protoporphyria generally favorable for patients with PCT 4.1. Case Vignette who are treated, the severity of underlying A 21-year-old Caucasian man liver ultimately drives prognosis. The presented with a rash and abnormalities on prevalence of HCV and or alcohol-related screening tests from a community health liver injury in conjunction with the hepatic fair. The patient stated he had had a “sun injury from PCT may result in advanced allergy” his “entire life” with development fibrosis or cirrhosis in these patients. of burning, tingling, and pain after even very Generally, liver transplant may be needed in short periods of exposure (~15 minutes). He these patients secondary to alcohol or HCV- had seen multiple pediatric specialists related liver disease. These patients are at without a definitive diagnosis. He endorsed increased risk for HCC, and should be a history of depressed affect as a result of screened with abdominal ultrasound and avoiding sunlight and had undergone a AFP every six months. Screening for varices cholecystectomy at age 20 (also had should be pursued as clinically appropriate. undergone liver biopsy during that operation), but otherwise stated he had been 3.6. Hepatoerythropoietic Porphyria well. He was afebrile with unremarkable (HEP)---Severe Homozygous/Compound vital signs and brought recent lab results that Heterozygous Form of PCT showed a cholestatic liver injury with serum HEP is an uncommon inherited alkaline phosphatase 220 IU/L, total cutaneous porphyria which results from bilirubin 2.2 mg/dL, AST 49 IU/L, and ALT severe deficiency of UROD, usually due to 51 IU/L. He also had a mild hypochromic, compound heterozygous defects, or, rarely, a microcytic anemia with blood hemoglobin [49,50] homozygous defect. Notably, the 10.8 g/dL and an MCV of 77 FL and enzyme defect occurs in all cells and tissues. hypovitaminosis D with a level of 19 ng/mL This condition is rare, and typically presents (ref range 30-100). Upon review of his prior in infancy with severe photosensitivity with evaluation, his liver biopsy showed crystal the formation of blisters and vesicles, closely depositions which were birefringent on resembling the cutaneous findings of polarized microscopy with a Maltese cross congenital erythropoietic porphyria (CEP) in pattern, sparse biliary canaliculi plugging children or PCT in adults. Management is with brown pigment, as well as early difficult and yields less definitive results bridging fibrosis; his gallbladder contained compared to other porphyrias. Avoidance of pigmented stones. He had undergone sunlight, protection of the skin, and prompt urinary porphyrin studies, which were management of infectious complications is normal, shortly after his cholecystectomy. paramount. Data supporting the use of iron Physical examination revealed pale skin with removal and antimalarial drugs have been hyperkeratotic patches on his knuckles, nose, disappointing. and perioral area, but was otherwise normal. Liver transplantation can be utilized Labs from his current visit showed markedly for treatment, as the overproduction of elevated erythrocyte protoporphyrin levels porphyrins occurs predominately in the liver. (2150 mcg/dL, ref range 20-80), with 5% However, because the defect is present in all being zinc protoporphyrin and 95% metal- cells, overproduction of porphyrins may free protoporphyrin. Plasma porphyrin was persist after liver transplant, and bone also increased, 18 mcg/dL (ref range 0-1.0), marrow transplant may also be needed for and with fluorescence emission peak at 634 definitive management.[51] nm, following excitation by the Soret band

Copyright 2017 KEI Journals. All Rights Reserved Page │12 Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs of blue light (410 nm peak for excitation). lichenification may develop, as was noted Based upon these results, as well as the with the patient in the above clinical history and physical examination, a vignette, and these lesions principally affect diagnosis of classical EPP was made. Gene the knuckles and face in either a malar or mutation analysis of the FECH gene perioral distribution.[9,52] revealed a nonsense mutation on one allele There are common coexisting clinical (p C411X) and the low-expressing common findings in patients afflicted with EPP such alteration on the other allele (IVS3-48 T>C), as iron deficiency anemia, hypovitaminosis confirming classical erythropoietic D, decreased quality of life, pigment protoporphyria due to deficient activity of gallstones, and liver dysfunction varying FECH. from mild elevations in liver enzymes to fulminant hepatic failure.[53-55] Iron 4.2. Clinical Features deficiency anemia is seen in approximately The prodrome and subsequent half of patients with EPP, and some dermatologic changes associated with EPP circumstantial evidence suggests that present a unique challenge in diagnosis, as symptoms may improve with iron repletion, the phenotype varies widely and may mimic although the opposite effect also has been more common presentations such as contact described.[52, 56-59] Gallstones are seen in dermatitis, solar urticaria, drug eruptions, approximately a quarter of patients, and EPP [9] and other cutaneous porphyrias. should be suspected in all patients with Stereotypical presentation of EPP pigment gallstones, especially in those involves a painful reaction to even brief without evidence of hemolysis. Decreased exposure to sunlight. The average age of quality of life and vitamin D deficiency stem onset is four years-old based on data from from the necessity of avoiding sunlight. the largest cohort available, and symptoms Liver disease, as will be discussed in detail, can begin after fewer than ten minutes of sun varies in its severity, though typically exposure – the majority of patients have presents as a cholestatic liver injury due to symptoms within 30 minutes.[52] The intracellular and canalicular crystal duration to onset of symptoms has been deposition. Of note, liver disease, as with shown to be directly related to the levels of other clinical manifestations of EPP, becomes more prevalent with higher ePP erythrocyte protoporphyrin (ePP), with [52] higher levels portending a lower tolerance to levels. light exposure.[52] Typically patients develop “burning” (91%), “tingling” (78%), 4.3. Pathogenesis and “itching” (78%) with light exposure Classical EPP stems from a genetic which, with continuing light exposure, defect which affects the inner mitochondrial progresses to erythematous, edematous, and enzyme, ferrochelatase (or FECH).[60] When occasionally petechial lesions on the deficient, as in EPP, FECH is reduced in its exposed skin that may last for hours to days ability to convert protoporphyrin (PP) into and are typically refractory to even high- heme.[9] The final step in heme biosynthesis, potency analgesia.[52] Of importance, and in namely insertion of Fe+2 into PP, performed notable contrast to other forms of cutaneous by ferrochelatase converts the fluorescent PP porphyria, such as PCT, HEP, CEP, or VP, molecule into non-fluorescent heme (Figure vesicles and blisters are distinctly 1).[9] In patients afflicted with EPP, FECH uncommon and only occur with extended activity is markedly reduced to exposure to sunlight.[9] As EPP is a chronic approximately 10-30% of normal controls; cutaneous porphyria, hyperkeratosis and thus the end-product of decreased FECH

Copyright 2017 KEI Journals. All Rights Reserved Page │13 Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs activity is accumulation of PP.[9,54] PP is a which the FECH gene is unaffected but strongly lipophilic molecule which allows rather in which there is a gain-in-function for it to pass from erythrocytes to plasma mutation (usually a deletion near the C- and subcutaneous tissues.[62] As opposed to terminal) of the 5-aminolevulinate synthase- porphyria cutanea tarda and congenital 2 (ALAS2) gene, which is located on the X erythropoietic porphyria where reactive chromosome, hence the name X-linked species are in circulation, in EPP, PP is PP.[7,63] About 5-10% of patients with the deposited into the skin because of the protoporphyric phenotype have XLPP.[64-66] lipophilic properties.[52] The aforementioned The levels of zinc PP in erythrocytes are fluorescent properties of PP become decidedly higher in XLPP, helping clinically evident after exposure to light, distinguish the two entities on diagnostic specifically blue light within the Soret band testing. Subjects with XLPP tend to have region (380-420nm), which results in higher levels of ePP, more severe clinical excitation of the PP molecule into a high disease, and higher risks of development of energy triplet state.[62] As these higher PP hepatopathy. energy molecules return to lower energy states, they give rise to oxygen-containing 4.4. Diagnosis and Management free radicals that damage the tissues and Diagnosis of EPP/XLPP requires vasculature where PP has deposited. It documentation of elevated ePP levels. The should be noted that blue light passes screening test is total blood porphyrin with through windows and is produced by high- reflex testing of metal-free PP and zinc PP. intensity light bulbs, namely, those used in If total blood porphyrins are elevated, and medical and dental procedures. Because PP metal-free PP is >90%, then sequencing of is strongly lipophilic, any circulating PP is the FECH gene will usually confirm EPP. If cleared from the circulation only by uptake total blood porphyrins are elevated but the into hepatocytes and subsequent secretion metal-free PP is 50-85% (with the remainder into the bile. Thus, the urine is clear of PP being zinc PP), exon 11 of the ALAS2 gene and testing for urinary porphyrins is should be sequenced as this likely represents ineffective for diagnosis of EPP or XLPP. XLPP. Most of the gain-of-function Genetic mechanisms of EPP have been mutations in ALAS2 are deletions of exon elucidated and originate from mutations of 11, which is a mutational ‘hotspot.’ the FECH gene, which is located on [61] The mainstay of an effective EPP chromosome 18q21.3. A majority of EPP treatment regimen, at this juncture, is cases are the result of a FECH mutation avoidance of blue light. Importantly, [missense, nonsense, frame shift, or transparent sunscreens block only ultraviolet deletion] on one allele in trans with the light and are ineffective in protecting EPP common hypomorphic variation in intron 3 patients from the damaging effects of blue (IVS3-48 T>C) on the other allele, as in the light.[9] Occasionally, and typically in those case presented above. Much less common, with darker complexions, light tanning can but still important entities within the genetic help extend the symptom-free interval with underpinnings of EPP are a FECH mutation exposure to sunlight.[67] Because of the on both alleles and an acquired form of the prevalence of gallstones and liver injury due FECH mutation, typically from a myeloid to crystallization of the PP during its disorder. excretion in bile, surveillance for gallstones More recent data have unveiled a is warranted on an annual basis and liver closely related phenotype with similar function testing is warranted on a semi- [68] accumulation of PP, namely, XLPP, in annual basis. Of note, rising ePP levels

Copyright 2017 KEI Journals. All Rights Reserved Page │14 Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs may be a harbinger of liver disease and for these issues and iron and vitamin D should be monitored more closely, supplementation provided as necessary. concomitantly with liver function tests.[52] Various other modalities of treatment have Given the risk of liver dysfunction due to been suggested, though convincing data for high PP levels, hepatotoxins should be their use are limited. These include high avoided and vaccination against viral dose cimetidine, activated charcoal, hepatitis A and B should also be performed. colestipol, beta-carotene, plasmapheresis, Anything that causes cholestasis is likely to red blood cell exchange transfusion, and make EPP/XLPP markedly worse. The intravenous heme.[68-74] Table 4 provides a commonality of anemia and hypovitaminosis summary of principles of management of D implies that patients should be screened EPP and XLPP.

Table 4. Summary of Management of EPP and XLPP

Management/treatment Monitoring / Comments Behavioral  Avoid sunlight Most commercial sunscreen products of little or  Utilize appropriate no value because they do not block long UV- sunscreen / clothing blue light (Soret band). Opaque zinc or titanium  Alcohol and tobacco oxide pastes are effective. cessation  Light tanning Tanning is generally recommended in those with darker complexions. Laboratory and  Annual or semi- diagnostics annual liver function ePP levels should be monitored concomitantly testing with liver testing.  Annual surveillance for gallstones Vaccination  Ensure vaccination and against hepatitis A Iron deficiency and vitamin D are common but supplements and B routine screening intervals have not been well  Replete vitamin D defined. and iron as necessary Medications  Afamelanotide 16mg Afamelanotide is pending US FDA approval. subcutaneous injection every 60 Numerous additional therapies have been days proposed with minimal or conflicting evidence. ePP, erythrocytic protoporphyria; mg, milligram; US FDA, United States Food and Drug Administration.

Progressive liver dysfunction may The severity of EPP/XLPP is generally ultimately necessitate orthotopic liver less in patients with greater natural skin transplantation; however, the underlying pigmentation, such as in African-Americans, physiology of liver dysfunction remains and compared to fair-complexioned Caucasians. thus, bone marrow transplantation (which, if Patients with greater innate skin successful, is curative) is occasionally pigmentation may be able to gradually considered for this reason.[75,76] increase their endogenous eumelanin by

Copyright 2017 KEI Journals. All Rights Reserved Page │15 Medical Research Archives, Vol. 5, Issue 9, September 2017 Porphyrias – An Overview and Update for Physicians and their Staffs graded doses of sunlight in the spring. 5. Summary and Conclusions Drugs that stimulate eumelanin production The porphyrias are a group of eight show promise as therapy. One such drug, diseases, due mainly to inherited defects in afamelanotide, has been approved for genes and enzymes of normal heme restricted use in Europe by the EMA. biosynthesis. They present clinically in Pending United States Food and Drug three different ways, as summarized above Administration approval, afamelanotide may in the clinical vignettes presented: 1. Acute become an option for EPP/XLPP patients porphyrias--As acute attacks of severe pain, also in the United States, as it has been usually abdominal, in women aged 18-45 shown to reliably increase the symptom-free years, often with tachycardia, systemic time during light exposure and improve [77-79] arterial hypertension, and passage of dark quality of life. Afamelanotide is a reddish to purple colored urine, which may congener of α-melanocyte-stimulating become even darker after exposure to light hormone, which works to increase [67] and air, especially at warm room production of eumelanin. Afamelanotide temperatures; 2. Porphyria cutanea tarda--As increases eumelanin without the need for skin lesions especially on the backs of the sunlight exposure; this well-tolerated hands and forearms, and sometimes also the therapy helps block the harmful effects of neck, ears, and head (areas of chronic sun blue light while also reducing cytokine exposure), occurring mainly in middle-aged production, which helps reduce [67,78,79] men who drink alcohol, have iron overload, inflammation. and/or HCV infection; and 3. EPP/XLPP-- As acute almost immediate photosensitivity, 4.5. Prognosis with itching, burning, and pain of skin EPP/XLPP is a chronic disease, and, if following minutes of exposure to sunlight. managed appropriately, serious Clinicians need to keep these diagnoses in complications can usually be avoided. Still, mind and especially need to order the correct significant limitations in quality of life key tests to establish or to exclude the remain for affected individuals. Severity of diagnosis of a porphyria. There are new disease has been shown to relate to higher treatments that are under study for these ePP levels as well as lighter disorders, especially Givosiran for acute [51] complexions. The most serious porphyrias and direct-acting antiviral drugs consequence of EPP/XLPP lies in the for PCT in the setting of HCV infection. hepatic dysfunction that occurs in There also is evidence that some patients approximately 5% of cases, and with EPP/XLPP may respond favorably to unfortunately, progresses to end-stage liver iron replacement therapy. At our medical [9] disease in 3-5% of patients. Of note, center and others of the Porphyrias higher levels of ePP and plasma PP levels Consortium of the USA, we are actively increase the risk of PP hepatopathy. Such studying these newer treatments in organized higher levels occur especially in XLPP clinical trials, and we welcome inquiries (particularly males) to as does missense or from physicians and other providers who nonsense mutations of both alleles of the may have subjects eligible for these studies. [51] FECH gene. Genetic testing is Please contact Dee Faust recommended to verify the diagnosis as well ([email protected]; phone: 336- as to help guide counseling for family 713-1441) or Herbert L. Bonkovsky, members. ([email protected]) for more information or to refer patients for these studies. Continuing research is the key to improving care for these patients.

Acknowledgements: This research initiative of the Office of Rare Diseases was supported in part by the Porphyrias Research (ORDR), NCATS, and is funded Consortium (U54 DK083909), which is a through a collaboration between NCATS part of the NCATS Rare Diseases Clinical and the NIDDK. Research Network (RDCRN). RDCRN is an

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