ABSTRACT
We report 2 patients with atypical glycogen storage disease type Ib without neutropenia or infectious complications. Neither patient was deficient in hepatic glucose-6-phosphatase activities in microsome-disrupted homogenates; both had mutations in the glucose-6-phosphate transporter gene, suggesting an allelic variant of glycogen storage disease type Ib.
Subject(s)
Glucose-6-Phosphatase/metabolism , Glucose-6-Phosphate/genetics , Glycogen Storage Disease Type I/enzymology , Glycogen Storage Disease Type I/genetics , Adult , Child , Glucose-6-Phosphatase/genetics , Glycogen Storage Disease Type I/diagnosis , Humans , Mutation , NeutropeniaABSTRACT
Serum phenylalanine concentrations decreased in 4 patients with hyperphenylalaninemia after loading with tetrahydrobiopterin. There were no abnormalities in urinary pteridine excretion or in dihydropteridine reductase activity. However, mutations were detected in the phenylalanine hydroxylase gene, suggesting a novel subtype of phenylalanine hydroxylase deficiency that may respond to treatment with cofactor supplementation.
Subject(s)
Antioxidants/therapeutic use , Biopterins/analogs & derivatives , Phenylalanine Hydroxylase/deficiency , Phenylketonurias/diagnosis , Phenylketonurias/drug therapy , Administration, Oral , Adolescent , Biopterins/therapeutic use , Child , DNA Mutational Analysis , Dihydropteridine Reductase/urine , Drug Monitoring , Female , Humans , Male , Mutation/genetics , Neonatal Screening , Phenylalanine/blood , Phenylalanine Hydroxylase/genetics , Phenylketonurias/genetics , Phenylketonurias/metabolismABSTRACT
We developed a new enzymatic assay for the glycine cleavage system that used Epstein-Barr virus-transformed lymphoblasts instead of liver biopsy specimens. Patients with nonketotic hyperglycinemia from a deficiency of P-protein could be clearly distinguished from control subjects by activities in their lymphoblasts, suggesting the clinical usefulness of this method.