title: Recurrent myoglobinuria in a child with mental retardation: phosphoglycerate kinase deficiency.
abstract: 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.
authors.affiliation: Department of Pediatrics, Hamamatsu University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sugie
authors.forename: Y
authors.initials: Y
authors.lastname: Sugie
authors.forename: M
authors.initials: M
authors.lastname: Nishida
authors.forename: M
authors.initials: M
authors.lastname: Ito
authors.forename: S
authors.initials: S
authors.lastname: Tsurui
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: R
authors.initials: R
authors.lastname: Miyamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: 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*
chemical_list: D010735:Phosphoglycerate Kinase