Recurrent myoglobinuria in a child with mental retardation: phosphoglycerate kinase deficiency.
We report the case of an 11-year-old mentally retarded boy with recurrent myoglobinuria precipitated after a generalized tonic-clonic convulsion. No hemolysis was noted. Ischemic forearm test revealed no rise of venous lactate, suggesting a metabolic defect in an anaerobic glycolytic pathway. Histochemistry studies of the quadriceps muscle showed a normal appearance, but electron microscopy confirmed a moderate increase of the glycogen content in muscle. Direct measurement of glycolytic enzymes demonstrated a marked decrease of phosphoglycerate kinase (PGK) activity in muscle (4.4% of control mean) and hemolysate (8% of control mean). Enzyme characteristics of PGK from our patient (PGK Hamamatsu) using hemolysate demonstrated that it had normal Michaelis constants (Km), normal thermal stability, and a normal pH curve. The reason that hemolytic anemia was absent is uncertain. We concluded that a systematic enzyme analysis of the glycolytic pathway, especially of PGK, should be performed on myoglobinuric patients who are males, or who have an X-linked inheritance as suggested by the family history.
Sugie
H
H
Department of Pediatrics, Hamamatsu University School of Medicine, Japan.
Sugie
Y
Y
Nishida
M
M
Ito
M
M
Tsurui
S
S
Suzuki
M
M
Miyamoto
R
R
Igarashi
Y
Y
D001706:Biopsy; D002648:Child; D006019:Glycolysis; D006801:Humans; D008607:Intellectual Disability / Q000201:enzymology* / Q000235:genetics; D008297:Male; D008854:Microscopy, Electron; D009132:Muscles / Q000473:pathology; D009212:Myoglobinuria / Q000201:enzymology* / Q000235:genetics; D010735:Phosphoglycerate Kinase / Q000172:deficiency*; D012008:Recurrence; D012206:Rhabdomyolysis / Q000201:enzymology*
D010735:Phosphoglycerate Kinase