P.15.5 An unsual phenotype of late onset desminopathy

Abstract

Desminopathies are a clinically relatively diverse group of myofibrillar myopathies with more than 40 mutations in desmin (DES) gene reported. The phenotype includes both distal, proximal or scapuloperoneal myopathies and/or cardiac myopathy and eventually respiratory failure. The disease onset may vary from childhood to late adulthood. Our patient is a 56 year old male with no history of neuromuscular disorders in the family. He has diabetic neuropathy causing sensory symptoms, distal lower leg atrophy, and areflexia in the lower extremities. Muscle symptoms started at age 40 with proximal weakness in the lower limb muscles. There is milder proximal weakness also in the upper limbs and neck flexors, but no other apparent axial weakness. CK levels have been elevated from 300 to 1000 IU/L and electrophysiology showed myopathic changes in addition to neuropathy. There are no respiratory symptoms and no cardiomyopathy on echocardiography to date. Muscle biopsy showed very minor myofibrillar myopathy, with rimmed and non-rimmed vacuolar pathology and on electron microscopy granulofilamentous aggregates. Severely affected muscles on MRI were gastrocnemius, peroneus longus, sartorius, semitendinosus and vastus lateralis suggestive of desminopathy, and a previously known pathogenic mutation p.S13F in DES gene was identified. The most peculiar finding clinically and on MRI was large bulging hypertrophic paravertebral muscles in the lumbar region, whereas, in the thoracal region paravertebral muscles were atrophic and replaced by fat.