Late onset distal myopathy and dysphagia due to myotilinopathy



Poster Number: M244


Al-Alya AlSabah, MD FRCPC, UCLA, Payam Soltanzadeh, MD, UCLA

77 year old man with German-English ancestry presented with three year history of dysphagia and inability to walk as fast as he used to. On examination, he was found to have bilateral weakness (4/5 MRC scale) in foot dorsiflexors. He did not have shortness of breath, cardiac dysfunction or positive family history of myopathy but his father died of poliomyelitis infection. Electrodiagnostic investigations showed irritable myopathy affecting the upper and lower extremities as well as the thoracic paraspinal muscles. Additionally, myotonic discharges were seen in deltoid and first interosseous muscles.. Polyphasic mixed small and large motor units were observed in distal muscles. Echocardiogram, pulmonary function test and sleep studies were all reported to be normal. Genetic testing was negative for myotonic dystrophy type 1, 2, and Pompe’s disease. HcN1A antibody was also negative.An extensive genetic neuromuscular panel showed a pathogenic heterozygous mutation in the myotilin gene (MYOT c.179C>T (p.Ser60Phe)). This gene encodes a cytoskeletal protein which plays a significant role in the stability of thin filaments during muscle contraction. This protein binds F-actin, cross links actin filaments, and prevents latrunculin A-induced filament disassembly. Mutations in MYOT gene have been associated with myofibrillar myopathy. Myotilinopathy should be considered as a cause of late onset distal lower extremity weakness and/or neuromuscular bulbar deficits. Myotonic discharges can be seen in myotilinopathy.