Discovery of a new mutation in the desmin gene in a young patient with cardiomyopathy and muscular weakness

Abstract

A 25-year-old woman with a five years history of syncope, mild left ventricular hypertrophy and moderately enlarged atria, was diagnosed with third degree atrioventricular heart block alternating with atrioventricular heart block 2:1, and received a dual chamber pacemaker. After three years of evolution, she developed atrial fibrillation, marked biatrial enlargement, severely depressed longitudinal myocardial velocities, associated with mild girdle weakness and slight increase in creatine kinase level. The diagnosis of restrictive cardiomyopathy with mild skeletal myopathy imposed the screening for a common etiology. Skeletal muscle biopsy revealed the morphological picture of myofibrillar myopathy with sarcoplasmic aggregates, immunoreactive for desmin and other ectopic proteins on immunohistochemistry, appearing as granulofilamentous material at ultrastructural level. Western blot analysis confirmed the desmin overexpression. Genetic testing identified a heterozygous missense variant DES rs869025381, c.1297C>A, p.(Pro433Thr), not previously reported. This is not only the first confirmed Romanian patient with myofibrillar myopathy with clinical features of severe restrictive cardiomyopathy associated with mild skeletal myopathy, but also a case which adds up to the known mutational spectrum in desminopathy.