Glucose-6-phosphate dehydrogenase (G-6-PD) mutations in Mexico: four new G-6-PD variants

Screening for mutations at the G-6-PD gene by PCR-SSCP combined with restriction enzyme analysis and DNA sequencing was performed in nine G-6-PD deficient individuals with negative results for the presence of the most frequent G-6-PD mutations previously observed in Mexican population. The variants G-6-PD Valladolid(406T), G-6-PD Durham(713G), and G-6-PD Viangchan(871A) and four new G-6-PD mutant alleles were identified. The new mutations are located at cDNA nt 376 A --> T (126 Asn --> Tyr), nt 770 G --> T (257 Arg --> Leu), nt 1094 G --> A (365 Arg --> His), and nt 1285 A --> G (429 Lys --> Glu) and they were named G-6-PD San Luis Potosi, G-6-PD Zacatecas, G-6-PD Veracruz, and G-6-PD Yucatán, respectively. To date, a total of 18 different G-6-PD variants have been observed in Mexico and several of them are common in Africa, South Europe, and Southeast Asia.     

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.     

Erythrocytosis due to bisphosphoglycerate mutase deficiency with concurrent glucose-6-phosphate dehydrogenase (G-6-PD) deficiency

A 28-year-old asymptomatic male of Iranian Jewish (Meshadi) heritage was found on routine exam to have an erythrocytosis (RBC = 6.22 x 10(12)/l, Hgb = 19.2 g/dl, Hct = 58.9%). Splenomegaly was absent on physical exam. There was no family history of erythrocytosis. His oxygen dissociation curve was left-shifted with a p50 of 19 mmHg (normal = 25-32 mmHg). Hemoglobin electrophoresis showed no abnormalities. DNA sequencing of the hemoglobin beta globin gene and both alpha globin genes did not reveal a mutation. A 2,3-bisphosphoglycerate (BPG) level was markedly decreased at 0.3 micromol/g Hb (normal = 11.4-19.4 micromol/g Hb). The patient's bisphosphoglycerate mutase (BPGM) enzyme activity was also markedly decreased at 0.16 IU/g Hb (normal = 4.13-5.43 IU/g Hb). A red cell enzyme panel revealed a markedly decreased G-6-PD level (0.3 U/g Hb, normal = 8.6-18.6 U/g Hb). His parents and a brother were also available for evaluation. Both parents showed normal 2,3-BPG levels but BPGM activity approximately 50% of normal. Paradoxically, the brother showed normal BPGM activity but a slightly decreased 2,3-BPG level. All family members had markedly decreased G-6-PD activity. DNA sequencing of the BPGM gene showed the propositus to be homozygous for 185 G-->A, Arg 62 Gln in exon 2. Thus, the erythrocytosis in this patient is secondary to low 2,3-BPG levels, due to a deficiency in BPG mutase. This appears due to consanguinity within this family.     

Severe jaundice in a patient with a previously undescribed glucose-6-phosphate dehydrogenase (G6PD) mutation and Gilbert syndrome

A patient with chronic hemolytic anemia and G6PD deficiency was noted to be severely jaundiced and to have a high serum ferritin level. Analysis of his DNA revealed only heterozygosity for the c.187 C-->G (H63D) mutation of HFE, but showed that he was homozygous for the UDP glucuronosyltransferase promoter mutation of Gilbert's disease and that he had a previously undescribed mutation of G6PD, c.832 T-->C (Ser278Pro). The new variant was named G6PD La Jolla.     

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.     

Characterization of a new glucose-6-phosphate dehydrogenase variant: G6PD Central City

Glucose-6-phosphate-dehydrogenase deficiency is the most common disease-producing enzyme deficiency in man. This paper describes a new glucose-6-phosphate-dehydrogenase variant discovered during the evaluation of an episode of acute hemolytic anemia in a 62-year-old black male, which was temporally related to the ingestion of Tolbutamide. The hemolysis resolved within 10 days despite continuation of Tolbutamide. The erythrocyte glucose-6-phosphate-dehydrogenase activity was significantly decreased, and its electrophoretic mobility was indistinguishable from wild type enzyme, though faster on starch gel with tris, borate, and phosphate buffers. The enzyme had a biphasic pH optimum reduced Km for G-6-P and NADP, decreased utilization of deamino-NADP, and reduced Ki for NADPH. Because the kinetic properties of this enzyme were unique, we have designated it as G6PD Central City.     

A glucose-6-phosphate dehydrogenase variant, Gd(-) Santamaria found in Costa Rica

Red cell glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-chromosomal-linked abnormality often associated with hemolytic anemia. The G6PD variants obtained from 2 unrelated males, one associated with enzyme deficiency and history of hemolytic jaundice, and the other associated with enzyme deficiency but no hemolytic problems, were examined. Although the 2 subjects have no known consanguinity, the two enzymes could not be distinguished from each other in respect to their electrophoretic mobilities and kinetic properties, both exhibiting slower than normal anodal electrophoretic mobility, lower Km for G6P and NADP and higher rate of utilization of 2-deoxy-G6P and deamino-NADP. An unique double-banded pattern was observed in starch gel electrophoresis at pH 7.0 and pH 8.6. The variant is distinguished from all reported Gd variants, and it is designated Gd(-) Santamaria.     

Molecular abnormality of a unique japanese glucose-6-phosphate dehydrogenase variant (G6PD Kobe) with a greatly increased affinity for galactose-6-phosphate

Systematic molecular analysis of a Japanese class 1 glucose-6-phosphate dehydrogenase (GGPD) variant (G6PD Kobe) cONA revealed a unique nucleotide substitution (1318 C to T) in exon 11, which predicts a substitution of leucine for phenylalanine at residue 440. This substitution is located in a region surrounding the putative structural NADP-binding domain. The markedly abnormal kinetics of glucose-6-phosphate (GGP) of GGPD Kobe suggest the interaction between both NADP and G6P binding sites. © 1994 Wiley-Liss, Inc.     

Molecular characterization of a German variant of glucose-6-phosphate dehydrogenase deficiency (G6PD Aachen)

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-chromosome-linked hereditary disorder. Clinically, patients with G6PD deficiency often present with drug- or food-induced hemolytic crises or neonatal jaundice. G6PD is involved in the generation of NADPH and reduced glutathione. In contrast to American, Mediterranean, and African ancestries, only few variants are known from Middle and Northern Europe. We describe the molecular characterization of a distinct variant from the northwestern area of Germany, G6PD Aachen. The sequence of the G6PD gene from three afflicted males was found to be hemizygous at cDNA residue 1089 for a C-->G mutation with a predicted amino acid change of Asn363Lys. The 1089 C-->G point mutation is unique, but produces the identical amino acid change found in a Mexican variant of G6PD deficiency, G6PD Loma Linda. This G6PD-deficient variant is caused by a 1089 C-->A mutation. The 363-amino-acid replacement is located outside a known mutation cluster region between amino acid residues 380 and 450, but may disrupt or weaken dimer interactions of G6PD enzyme subunits.     

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.