Miyoshi myopathy in Saudi Arabia: clinical, electrophysiological, histopathological and radiological features.

Miyoshi myopathy (MM) is a rare autosomal recessive distal myopathy linked to chromosome 2p12-14 that has not been described in Saudi Arabia. A Saudi family with five siblings aged 3-25 years, an unrelated 18-year-old woman and a 40-year-old man with MM were identified. All patients underwent a neurological examination, serum chemistry, electromyography and MRI of the legs. Four patients underwent a muscle biopsy that was processed for routine enzyme histochemistry and immunocytochemical analyses for dystrophin and adhalin (alpha-sarcoglycan). The two sporadic and two familial cases showed classic findings of MM, including early adult onset, preferential involvement of gastrocnemius muscles, markedly elevated serum creatine kinase levels and dystrophic-appearing muscle without vacuoles. Magnetic resonance imaging revealed selective involvement of the posterior compartment muscles and myoedema by STIR sequences. The remaining three familial cases had elevated serum creatine kinase levels and two also had early myopathic findings by EMG suggestive of MM.