Combined defects of muscle phosphofructokinase and AMP deaminase in a child with myoglobinuria.

A 14-year-old boy with exercise-related myalgia and cramps had several episodes of myoglobinuria since early childhood. An episode at 2 years of age caused acute renal failure. Histochemical and biochemical analysis of muscle showed a combined defect of phosphofructokinase (PFK) and adenosine monophosphate (AMP) deaminase. DNA analysis showed that the patient was homozygous for a G-to-C substitution at codon 39 of the PFK gene (previously described in an Italian patient) and for the common mutation found in AMP deaminase deficiency.