[Case of LGMD2A (calpainopathy) clinically presenting as Miyoshi distal myopathy]

We reported a 23-year-old woman with distal myopathy and highly elevated serum creatine kinase (CK) caused by calpainopathy. Although muscle weakness was not evident, a muscle CT scan revealed replacement by adipose tissue in the medial head of the gastrocnemius. The gluteus maximus and biceps femoris were also affected to a lesser degree, but the lateral head of the gastrocnemius was preserved. A histological study of a biopsied specimen of the biceps brachii revealed obvious variation in fiber size and a few necrotic or regenerating fibers. Rimmed vacuoles or lobulated fibers were absent in vacuoles. Although the clinical features suggested Miyoshi's distal myopathy, gene analysis of calpain 3 revealed a c.802-9G > A mutation in intron 5 and a c.1319G > A (p.Arg440Gln) in exon 10. Mini-multiplex Western Blotting (MMW) of the patient's muscle showed no band in calpain 3 (p94) and calpain 3 30 kDa fragments and immunoblotting did not reveal any dysferlin abnormalities. Calpainopathy should be also considered in patients with clinical manifestations of Miyoshi distal myopathy.