Myoadenylate deaminase deficiency in a 5-year-old boy with intermittent muscle pain.

A 5-year-old boy with occasional pain of brief duration at the right or the left leg during exercise since the age of 4 years is reported. There was no weakness nor any other abnormality at the neurological examination. The serum creatine phosphokinase activity was elevated three times out of four. The electromyogram showed myopathic abnormalities in the biceps, it was normal in quadriceps and anterior tibial muscles. A quadriceps muscle biopsy was performed. There were no histological nor histochemical abnormalities at the routine techniques. However, a completely negative reaction with myoadenylate deaminase ( MADA ) stain was found. The MADA enzymatic activity in the muscle was very low. It is likely that the clinical syndrome is related to MADA deficiency.