Original Article New mutation of the identified in an extended Indian pedigree presenting with distal myopathy and cardiac disease

Atchayaram Nalini, Narayanappa Gayathri1, Pascale Richard2, Ana‑Maria Cobo3, J. Andoni Urtizberea3

Departments of Neurology, and 1Neuropathology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India, 2Department of Genetics, Pitié-Salpêtrière Hospital, 75651 Paris - France, 3 Department of Neurology, Neuromuscular Unit, Marin Hospital, 64700 Hendaye - France

Abstract

In this report, we describe a new mutation located in the coiled 1B domain of desmin and associated with a predominant cardiac involvement and a high degree of cardiac sudden death in a large Indian pedigree with 12 affected members. The index cases was 38‑year‑old man who presented with progressive difficulty in gripping footwear of 5 years Address for correspondence: duration with the onset in the left lower limb followed by right lower limb in 6 months. Dr. Atchayaram Nalini, 3 years from onset, he developed lower limb proximal and truncal muscle weakness. Department of Neurology, There was mild atrophy of the shoulder girdle muscles with grade 3 weakness, moderate National Institute of Mental Health wasting of thigh and anterior leg muscles with proximal muscle weakness and foot drop. and Neurosciences, Bengaluru, At 40 years, he had a pacemaker implanted. The 9 exons and intronic boundaries of the Karnataka, India. desmin gene were sequenced and a heterozygous nucleotide change c. 734A > G in E‑mail: [email protected] exon 3 was identified. Received: 04‑06‑2013 Review completed: 11‑09‑2013 Key words: cardiac pacing, cardiomyopathy, D esminopaty, desmin gene mutation, Accepted: 03‑12‑2013 distal myopathy

Introduction gene (DES) on 2q35 and mutations in this gene were first shown in MFMs.[3‑6] DES encompasses Desminopathy is a genetically heterogeneous group nine exons within an 8.4-kb region and encodes of disorders named myofibrillar myopathies (MFMs) 470 amino acids.[7] Desmin is composed of an α‑helical rod and are caused by mutations of desmin gene (DES), containing 303 amino acid residues, flanked by globular αB‑crystallin (CRYAB), myotilin (MYOT), Z band N‑and C‑terminal structures. The rod is interrupted in alternatively spliced PDZ‑containing (ZASP), several places, resulting in four consecutive α‑helical filamin C (FLNC), or Bcl‑2–associated athanogene‑3 segments, 1A, 1B, 2A and 2B, connected by short, (BAG3).[1,2] Human desmin is encoded by a single‑copy non‑helical linkers. This disorder is characterized by skeletal and cardiac myopathy with weakness in distal Access this article online leg muscles spreading proximally and leading eventually to tetraparesis and wheelchair dependence.[8] Desmin Quick Response Code: Website: www.neurologyindia.com is the main intermediate filament protein expressed in cardiac (2% of total protein), skeletal (0.35%) and smooth PMID: [9] *** muscle. It is a major component of Purkinje fibers. Clinical presentation is variable, often associated with DOI: cardiomyopathy and histopathologically characterized 10.4103/0028-3886.125269 by aberrant desmin aggregation in abnormal muscle

622 Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6 Nalini, et al.: DES mutation in distal myopathy fibers.[4,8,10] It is important to identify these patients early developed arrhythmia with frequent ectopic and missed as this would ensure prevention of sudden cardiac and beats at 35 years and had a pacemaker implanted for 2:1 other complications.[11] In the present report, we describe atrioventricular (AV) block. At 39 years, he developed a family with a new mutation located in the coiled 1B lower limb weakness, serum creatine kinase (CK) domain of desmin. 1,300 IU/l. Younger brother of the proband aged 33 years developed lower limb weakness at 27 years with no Case Report cardiac symptoms. Proband’s paternal grandmother required a pacemaker at 60 years of age. She expired The present case report is about a 38‑year‑old man, at age 69 years due to sudden cardiac arrest. Affected presented to our Institution in May 2010 with progressive grandmother’s elder brother had cardiac arrhythmias. asymmetrical onset lower limb distal muscle weakness His two sons had cardiac illness and one had a sudden of 5 years duration and proximal weakness of 2 years. death at 40 years. No further details are available. Clinical details of summarized in Table 1. In 2012 due to persistent electrocardiogram (ECG) abnormalities Examination of the proband’s radial pulse revealed and ectopic beats, he had a pacemaker implanted. frequent missed beats. There was mild bifacial weakness, Family history of similar illness in 12 members of the mild atrophy of shoulder girdles and moderate extended family was reported [Figure 1]. Father of the wasting of thighs and anterior leg muscles. Neck proband developed complete heart block at 42 years of flexors and upper limbs were moderately weak. Motor age and had a pacemaker implanted. At 1 year later, he power in lower limbs hips‑grade 3/5; abductors and developed progressive lower limb weakness. At 51 years adductors 4/5; knee extensors 4 ± 5 and flexors 2/5, noticed upper limb weakness and also required help of ankle and toe dorsiflexors 2/5 and plantar flexors 5/5. a walking stick. At 63 years, he had a sudden cardiac Deep tendon reflexes were normal. Gait was waddling death. Elder brother of the proband aged 40 years, with high steppage gait.

Table 1: Salient clinical symptoms in the proband and affected family members Parameter Proband Proband’s father Proband’s elder Proband’s Paternal brother younger brother grandmother Age at presentation (years) 38 ‑ 40 33 ‑ Age at onset (years) 33 42 35 27 60 Duration of illness (years) 5 ‑ 5 6 9 Symptom at onset Foot drop with weakness Foot drop with weakness Arrhythmia, ectopic LL distal and Arrhythmia of foot muscles of foot muscles beats proximal weakness Symm/asymm Asymm Symm Symm Symm ‑ LL proximal weakness Yes, at 35 years Yes, at 43 years Yes, at 39 years Yes No Distal LL weakness Yes Yes, at 43 years Yes, at 39 years Yes No Upper limb weakness No Yes, at 51 years No No No Trunkal weakness Yes Yes No No No Wasting Thighs and legs Thighs and legs ‑ No No Cardiac symptoms Nil Yes, complete heart block Yes No Yes at 42 years Pace maker implantation Yes, at 40 years Yes at 42 years Yes, at 37 years. Had 2:1 Yes, at 60 years atrioventricular block Sudden cardiac death ‑ Yes, at 63 years ‑ ‑ Yes, at 69 years LL ‑ Lower limb, Symm ‑ Symmetrical, Asymm ‑ Asymmetrical

Figure 1: Pedigree diagram depicting the proband and other affected members. Solid symbol-Only the proband was available for evaluation. Partially filled symbols: All other members reported to be affected with similar illness

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Investigations: Serum CK of 529 IU, myopathic The 9 exons and intronic boundaries of the DES were electromyography and normal motor and sensory sequenced and a heterozygous nucleotide change c. nerve conduction studies. Quadriceps muscle biopsy 734A > G in exon 3 was found [Figure 4]. At the protein revealed dystrophic changes with the presence of level, this substitution either introduces the missense vacuoles rimmed by red granular material. There mutation p.Glu245Gly or abolishes of 53% the adjacent were a significant number of atrophic fibers. Modified donor splice site resulting in a putative in‑frame gomori trichrome (MGT) stained sections also revealed skipping of exon 3 corresponding to the deletion of rimmed vacuoles and succinate dehydrogenase (SDH) residues p.Asp214‑Glu245. Nevertheless, in the absence enzyme staining showed a loss of reaction to oxidative of messenger ribonucleic acid (mRNA) analysis, we enzyme stain in the fibers. There was no tissue cannot speculate on the consequences of the variant at available for ultrastructural studies or additional the protein level. immunohistochemical staining [Figure 2]. Discussion ECG showed complete right bundle branch block with occasional ventricular premature complexes. 2D This is the first report of genetically confirmed Echocardiogram was normal. Magnetic resonance autosomal dominant desminopathy with cardioskeletal imaging (MRI) of the pelvis and thigh revealed severe presentation from India. The common pathological involvement of the gluteus maximus, minimus and pattern in myofibrillar myopathy is dissolution of medius, vastus lateralis, intermedius and medius, rectus , aggregation of degraded myofibrillar femoris, gracilis and sartorius. Semimembranosus, products and ectopic expression of is also semitendinosus, adductor longus and brevis were well‑described.[2] The clinical manifestations are moderately involved. Adductor magnus was well remarkably variable. Progressive skeletal myopathy preserved [Figure 3]. MRI of leg muscles was not done. is one of the clinical variants of desminopathy[12] and is observed in almost a quarter of patients.[13] The Genetic analysis illness generally starts at a later age than in individuals After written informed consent blood for genomic with other disease variants and the progression is deoxyribonucleic acid was drawn from 9 members commonly very slow. weakness is and transported to Paris, France for genetic analysis. typically known to start in distal leg muscles and spreads to proximal muscles. In advanced disease, all four limbs are affected.[12] The disease course in our proband and other family members was relatively slow with involvement of both distal and proximal muscles. Phenotypic variability is reported to depend on the type of inheritance and the location of mutations within the relatively large and structurally and functionally complex desmin molecule.[4] Clinical features have been a b characterized as severe childhood‑onset cardioskeletal myopathy adult‑onset skeletal myopathy with cardiac involvement, pure skeletal myopathy, cardiomyopathy with distal weakness, pure dilated cardiomyopathy and

c

a b

d c Figure 2: Transversely cut skeletal showing (a) myofibers Figure 3: Magnetic resonance imaging shows (a) severe involvement with vacuoles (b) significant numbers of atrophic fibers (c) modified gluteus maximus, minimus and medius (b) severe involvement of vastus gomori trichrome stained sections reveal vacuoles rimmed by red lateralis, intermedius and medius, rectus femoris, gracilis and moderate granular material (h) rimmed vacuoles, (d) loss of reaction to oxidative involvement of sartorius. Semimembranosus, semitendinosis, adductor enzyme stain succinate dehydrogenase in the fibers (h) longus and brevis (c) adductor magnus was well preserved

624 Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6 Nalini, et al.: DES mutation in distal myopathy

Figure 4: Electrophoregram corresponding to the sequence of the exon 3 of desmin gene: Top, reference sequence with the position of the splice site and the involved nucleotide. Bottom, sequence of the affected patients indicating the heterozygous c.734A>G distal myopathy with cardiac, respiratory, bulbar, facial semimembranosus. However, there was no difference and involvement. Distal, limb‑girdle in affection of semimembranosus and semitendinosus. phenotypes and scapuloperoneal weakness with variable In the anterior compartment, rectus femoris, vastus cardiac and respiratory involvement have been seen lateralis, intermedius and medialis are reported to be within a set of kindreds segregating with the p.Arg350Pro relatively spared in most patients.[10] However, in our desmin mutation.[14] Our family had the early adult patient all these muscles were severely affected. In onset form, with the onset before age 40 and distal limb lower legs: the peroneal muscles are known to display girdle phenotype with arrythmogenic cardiomyopathy significantly more lipomatous changes than the tibialis requiring pacemaker implantation. About 80% of anterior and muscles of the posterior compartment desminopathy families show classic autosomal dominant (soleus, medial and lateral gastrocnemius). pattern of inheritance, most with full penetrance.[4,13] Our family had this inheritance pattern with members The most consistent finding in muscle‑biopsy specimen affected in four generations. In the earliest generation has been reported to be the presence of bluish the affected members survived for long years after the accumulations in subsarcolemmal or centrally located onset of illness. areas immunoreactive on staining with against desmin. Rimmed vacuoles and small aggregates Muscle involvement on imaging in desminopathy of rods are also reported. In our patient many rimmed range from mild to severe.[10] In pelvic muscles: the vacuoles were noted. Dark‑blue inclusions have also been gluteus maximus muscle is significantly more involved reportedly identified on trichrome (MGT) staining. We than the gluteus medius and minimus muscles. In our did not detect these dark‑blue inclusions. Multiple nuclei, patient, all three muscles were equally and severely atrophic fibers and cytoplasmic bodies are reported to affected. In thigh: Semitendinosus, sartorius and be common. Our patients had plenty of atrophic fibers, gracilis are the most affected muscles exceeding the but no cytoplasmic bodies. SDH staining had revealed involvement of the adductor magnus, biceps femoris loss of reaction to oxidative enzyme stain in the fibers. and semimembranosus. Similarly in our patient, On electron microscopy (EM), myofibrillar disruption, sartorius and gracilis were more severely affected as fragments of thin and thick filaments, streaming Z bands compared to adductor magnus, biceps femoris and and deposits of dense, amorphous material are known

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Vrabie A, Goldfarb LG, Shatunov A, Nägele A, Fritz P, Kaczmarek I, et al. The enlarging spectrum of desminopathies: New morphological desminopathy. AV conduction abnormalities requiring findings, eastward geographic spread, novel exon 3 desmin mutation. urgent pacemaker implantation of a permanent Acta Neuropathol 2005;109:411‑7. pacemaker is a frequent feature. Hence, early detection of this disorder and elective pacemaker implantation How to cite this article: Nalini A, Gayathri N, Richard P, Cobo A, would be life saving. Clinical findings in addition to Urtizberea JA. New mutation of the desmin gene identified in an MR imaging of lower limbs and pathological findings extended Indian pedigree presenting with distal myopathy and are useful in differentiating distinct forms of MFMs and cardiac disease. Neurol India 2013;61:622-6. could guide in specific molecular genetic testing. Source of Support: Nil, Conflict of Interest: None declared.

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