New glucose-6-phosphate dehydrogenase mutations associated with chronic anemia

We have identified the glucose-6-phosphate dehydrogenase mutations responsible for enzyme deficiency in nine individuals with chronic nonspherocytic hemolytic anemia. We found the variants Tokyo, Iowa, Shinshu, and Guadalajara in British subjects and Kobe in an Italian. In addition we have determined the variant Corum has the mutation 820 G-- >A and have found in British subjects the mis-sense mutations 224 T-- >C, 488 G-->A and 833 C-->T which have not been described before. Some, but not all, of the mutations involve amino acids located near putative substrate binding sites.     

G6PD San Francisco: a new variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia

Congenital nonspherocytic hemolytic anemia in an adult male of Scandinavian ancestry was associated with virtual absence of G6PD activity in red cells. Characterization of G6PD purified from leukocytes using standard WHO techniques revealed diminished electrophoretic mobility, marked lability on heating at 46 degrees C, normal pH optimum and utilization of alternate substrates (2-deoxy G6P, D-amino NADP), elevated Km NADP, and striking susceptibility to NADPH inhibition. The variant G6PD, which appears to be unique, has been designated G6PD San Francisco. An unusual feature of the variant enzyme, susceptibility to inactivation by brief periods of dialysis, could be prevented by addition of 200 microM NADP to the dialysis solution. In red cells, where G6PD activity was essentially absent, regeneration of reduced glutathione was totally curtailed in vitro, while in leukocytes, where residual G6PD activity was approximately 60% of normal, hexose monophosphate shunt activity, oxygen consumption during phagocytosis, and bacterial killing were unimpaired. Thus, instability of the variant enzyme rather than its unfavorable kinetics appeared to be an important determinant of abnormal cell function.     

Association of glucose-6-phosphate dehydrogenase deficiency and X-linked chronic granulomatous disease in a child with anemia and recurrent infections

Patients with severe leukocyte G6PD deficiency may present with impairment of NADPH oxidase activity and a history of recurrent infections, mimicking the phenotype of chronic granulomatous disease. We report herein a child with recurrent infections who initially received the diagnosis of G6PD deficiency. His erythrocyte G6PD activity was reduced: 1.8 U/g Hb (normal: 12.1 +/- 2.1 U/g Hb). Further studies revealed that G6PD activity in neutrophils, mononuclear leukocytes, and Epstein-Barr virus-transformed B-lymphocytes from the proband was similar to healthy controls. Molecular studies showed that the G6PD deficiency was due a 202 G-->A mutation, the A- variant common in African ethnic groups. The proband also exhibited severely impaired respiratory burst activity, as observed in X-linked CGD. Sequence analysis of genomic DNA showed a 264 G-->A substitution at the 3' splice junction of gp91-phox exon 3. The cDNA sequence showed a deletion of gp91-phox exon 3, giving rise to an unstable or nonfunctional mutant gp91-phox and to the phenotype of X-linked CGD. We propose that clinicians treating a patient with G6PD deficiency during a severe infection episode consider the possibility of temporary or permanent impairment of the phagocytes' microbicidal activity and the eventual association of G6PD deficiency and chronic granulomatous disease.     

Glucose-6-phosphate dehydrogenase aveiro: a de novo mutation associated with chronic nonspherocytic hemolytic anemia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme abnormality. The clinical phenotype is variable but often predictable from the molecular lesion. Class I variants (the most severe forms of the disease) cluster within exon 10, in a region that, at the protein level, is believed to be involved in dimerization. Here we describe a de novo mutation (C269Y) of a new class I variant (G6PD Aveiro) that maps to exon 8. Mutant and normal alleles were found in both hematopoietic and buccal cells, indicating the presence of mosaicism. The available model of the protein predicts that this lesion lies in proximity to the dimer interface of the molecule. A possible mechanism to explain the severity of the defect is proposed. (Blood. 2000;95:1499-1501)     

Three new variants of glucose-6-phosphate dehydrogenase associated with chronic nonspherocytic hemolytic anemia: G-6-PD Lincoln Park, G-6-PD Arlington Heights, and G-6-PD West Town

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency was identified in three children who were evaluated because of chronic nonspherocytic hemolytic anemia. One child is of German extraction, another Puerto Rican, and the third Mexican. In each of the patients the hemolytic process was well compensated, but each had one or more episodes of anemia following exposure to an oxidant drug or with infections. The electrophoretic, functional, and kinetic properties of the mutant enzymes, derived both from the patients' erythrocytes and from cultured fibroblasts, allowed each to be distinguished from G-6-PD variants previously described.     

Effects of glucose-6-phosphate dehydrogenase deficiency upon sickle cell anemia

We studied the interactions of the A- variety of glucose-6-phosphate dehydrogenase (G6PD) deficiency and sickle cell anemia (HbSS) to see if G6PD deficiency influenced laboratory and clinical features of HbSS. A total of 801 male patients over age 2 had G6PD electrophoresis on cellulose acetate membranes. Assays of both G6PD activity and hexokinase activity were then done on all samples that had an electrophoretic pattern other than the normal wild type (GdB). The collection of clinical data used a standardized protocol. Using cluster analyses we classified 10.4% males to be G6PD deficient, while 18.4% had the functionally normal GdA+ enzyme. The prevalence of G6PD deficiency did not change significantly when age was stratified by decade, suggesting little survival advantage or disadvantage of the combination of G6PD deficiency and HbSS. Compared to patients who were not G6PD deficient, there were no significant differences in the hemoglobin concentration, mean corpuscular volume, reticulocyte count, bilirubin, or SGOT level in patients with HbSS who had G6PD deficiency. The incidence of painful episodes, sepsis, or acute anemic episodes was similar in both groups. Our results are consistent with recent studies of smaller numbers of patients that have found little influence of G6PD deficiency upon HbSS. Specifically, we found no evidence that G6PD enhanced the severity of hemolysis or increased the incidence of acute anemic episodes or sepsis in HbSS.     

G-6-PD Long Prairie: a new glucose-6-phosphate dehydrogenase mutant exhibiting normal sensitivity to inhibition by NADPH and accompanied by nonspherocytic hemolytic anemia.

The enzymatic properties of a new glucose-6-phosphate dehydrogenase (G-6-PD) variant (G-6-PD Long Prairie) were studied in a white patient with chronic nonspherocytic hemolysis. The red cells were found to have 2.3%-7.7% normal enzymatic activity. The mutant enzyme exhibited marked heat instability, an increased pH optimum, a moderately decreased Km for G-6-P, and increased utilization of 2-deoxyglucose-6-phosphate and deamino NADP. The Km for NADP and Ki for NADPH were both normal. G-6-PD Long Prairie is an interesting new G-6-PD variant that demonstrates that chronic hemolysis can be associated with modestly decreased G-6-PD activity despite normal sensitivity to inhibition by NADPH. Although increased sensitivity to inhibition by NADPH has been postulated to decrease intracellular enzyme activity, resulting in enhanced susceptibility to hemolysis in certain G-6-PD variants with only moderately decreased enzymatic activity, an alternative mechanism of hemolysis, possibly enzyme thermolability, exists in G-6-PD Long Prairie.     

Chronic nonspherocytic hemolytic anemia due to glucose-6-phosphate dehydrogenase deficiency: report of two families with novel mutations causing G6PD Bangkok and G6PD Bangkok Noi

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common hereditary enzymopathies worldwide. Mostly G6PD deficient cases are asymptomatic though they may have the risk of neonatal jaundice (NNJ) and acute intravascular hemolysis during oxidative stress. Chronic nonspherocytic hemolytic anemia (CNSHA) due to G6PD deficiency is rare. In Thailand, one case was reported 40 years ago and by biochemical study this G6PD was reported to be a new variant G6PD Bangkok. We, herein, report two families with CNSHA due to G6PD deficiency. In the first family, we have been following up the clinical course of the patient with G6PD Bangkok. In addition to chronic hemolysis, he had three acute hemolytic episodes requiring blood transfusions during childhood period. Multiple gallstones were detected at the age of 27. His two daughters who inherited G6PD Bangkok from him and G6PD Vanua Lava from his wife are asymptomatic. Both of them had NNJ and persistent evidences of compensated hemolysis. Molecular analysis revealed a novel missense mutation 825 G→C predicting 275 Lys→Asn causing G6PD Bangkok. In the second family, two male siblings are affected. They had NNJ and several hemolytic episodes which required blood transfusions. On follow-up they have been diagnosed with chronic hemolysis as evidenced by reticulocytosis and indirect hyperbilirubinemia. Molecular analysis revealed combined missense mutations in exons 12 and 13. The first mutation was 1376 G→T predicting 459 Arg→Leu (known as G6PD Canton) and the second one was 1502 T→G predicting 501 Phe→Cys. We designated the resulting novel G6PD variant, G6PD Bangkok Noi.