Myoglobinuria as first clinical sign of a primary alpha-sarcoglycanopathy

Myoglobinuria is a frequent complication of metabolic myopathies and may also occur in Duchenne and Becker dystrophies but is not a typical sign of limb-girdle muscular dystrophy. We describe an unusual presentation of alpha-sarcoglycanopathy with myoglobinuria at the onset of the disease. The boy presented an episode of dark urine, identified as presence of blood by a urine dipstick, occurred 10 days after an episode of fever and sore throat treated with antibiotics. He was admitted to the hospital and investigated for post-infectious nephritis, but further analysis revealed the presence of myoglobinuria. Immunohistochemistry on muscle tissue revealed absent expression of α-sarcoglycan confirmed by detection of a homozygous mutation in the alpha-sarcoglycan gene. Myoglobinuria has been previously reported four times in sarcoglycanopathies but only once in alpha-sarcoglycanopathy.