Recessive desmin-null muscular dystrophy with central nuclei and mitochondrial abnormalities

Abstract

missense mutations. However, very few families with a recessive mode of inheritance have also been recognized [2]. Desmin immunostaining of normal skeletal muscle shows uniform sarcoplasmic and subsarcolemmal localization, while affected muscles display cytoplasmic aggregates of misfolded filaments and disruption of the myofibrillar apparatus rather than absence of protein [2], so that individuals with desmin mutations are frequently categorized within the group of disorders known as myofibrillar myopathies. We describe a family with no history of neuromuscular or cardiac disorders with two siblings affected by autosomal recessive desminopathy manifesting as a slowly progressive, predominantly proximal muscle fatigue and weakness. The proband, a 12 year old boy, was born at term and had normal gross motor milestones, but presented poor head control when crawling, lack of facial expression and congenital ptosis. From the age of 3 he showed difficulty rising from the floor, jumping, running and going upstairs. The weakness was slowly progressive over the years and he remains independently mobile. He tires easily and benefits from short breaks. On examination he presented with shoulder, grip and hip muscle weakness, symmetrical scapular winging, mild thoracic scoliosis and mild bilateral calf hypertrophy. Muscle MRI features are shown in Fig. 1a. He shows an unusual pattern of swallowing, turning his neck to ingest food, but he has a good appetite and is generally healthy. Forced vital capacity (FVC) was 45 % of the predicted value in sitting. CK levels were raised up to 1,000 IU/L, cardiac examinations were normal. His 11 year old sister displayed a slightly less pronounced weakness, contractures of long finger flexors and shoulders and hyperextensible elbows as well as similar tiredness and swallowing habit as her brother. She has a small appetite with a weight below the 3rd centile and also presents a history of asthma and rare chest infections. Her FVC was 40 % of the predicted value Desmin is a muscle-specific intermediate filament that provides maintenance of cellular integrity and force transmission [2]. DES gene mutations cause a spectrum of adult-onset disorders, ranging from myopathies with and without cardiac involvement to cardiomyopathy without skeletal muscle involvement [3]. Distal and proximal weakness involving upper and lower limbs muscles are observed in most patients [9]. Desminopathies are usually inherited in an autosomal dominant fashion, predominantly with