G-6PD "ankara". a new G-6PD variant with deficiency found in a Turkish family.

A new G-6PD varient with enzyme deficiency is described in a 7-month-old Turkish boy without any hemolytic manifestation, except neonatal hyperbilirubinemia. The main characteristics of this variant were the following: Severe enzyme deficiency in erythrocytes (8% of normal), fast starch-gel-electrophoretic mobility (110% of normal), increased Ki NADPH with respect to NADP+, slightly biphasic pH curve, enzyme instability, in vivo and in vitro, decreased molecular specific activity (58% of normal).     

Phenotypic variation in red cell G-6PD deficiency in heterozygotes

Erythrocyte G-6PD activity in 69 heterozygotes has a log-normal distribution, a fact which cannot be solely attributed to random X chromosome inactivation. Others factors - genetic and individual - are suggested by intrafamilial clusting and post-natal variability of phenotype.     

Molecular analysis of three novel G6PD variants: G6PD Pedoplis-Ckaro, G6PD Piotrkow and G6PD Krakow

We present three novel mutations in the G6PD gene and discuss the changes they cause in the 3-dimensional structure of the enzyme: 573C-->G substitution that predicts Phe to Leu at position 191 in the C-terminus of helix alphae, 851T-->C mutation which results in the substitution 284Val--> -->Ala in the beta+alpha domain close to the C-terminal part of helix alphaj, and 1175T-->C substitution that predicts Ile to Thr change at position 392.     

G-6-PD Jalisco and G-6-PD Morelia: Two new Mexican variants

Summary Two new G-6-PD variants designated G-6-PD Jalisco and G-6-PD Morelia were identified in two unrelated Mexican families. An additional G-6-PD variant was found in each family: G-6-PD trinacria and G-6-PD A^-. In both families compound heterozygotes were identified. G-6-PD Jalisco and G-6-PD Morelia belong to Classes 3 and 4, respectively. G-6-PD Morelia is the first variant from its class with a high Km for NADP and a low Ki for NADPH.     

Leucocyte glucose-6-phosphate dehydrogenase (G-6-PD) activity in G-6-PD deficient Chinese

The activity of glucose-6-phosphate dehydrogenase (G-6-PD) in leucocytes was studied for erythrocyte G-6-PD deficiency using 49 hemizygous males, 16 heterozygous females, and 19 normal controls. The mean G-6-PD activity in leucocytes of the affected neonates (9.2 +/- 5.4 units) and the children (11.2 +/- 5.3 units) were significantly lower than those of normal newborns (22.9 +/- 5.1 units, P less than 0.01). Seventy percent of the effected newborns and 58% of the children with G-6-PD deficiency had the leucocyte enzyme activity of less than 13 IU/10(9)WBC. The leucocyte enzyme activity (14.6 +/- 8.6 units) of 16 heterozygous G-6-PD deficient mothers was also lower than that of normal controls (23.1 +/- 7.0 units). The present study thus concludes that, in G-6-PD deficient Chinese, the enzyme defect is demonstrable not only in erythrocytes but also in leucocytes.     

G6PD Toronto

Members of a Toronto family of Northern European ancestry were found to have a deficiency of red cell and white cell glucose 6-phosphate dehydrogenase (G6PD) activity. The hemizygous propositus had neonatal hyperbilirubinemia and subsequent episodes of hemolytic jaundice associated with respiratory infections and exposure to paint fumes. Characterization of the enzyme revealed that it was a variant which had not been previously described, and it was named 6GPD Toronto.This study was supported by grants MT 696 from the Medical Research Council of Canada and GM 15253 from the National Institutes of Health.     

G6PD Avenches and G6PD Moosburg: biochemical and erythrocyte membrane characterization

Two new G6PD variants with severe enzyme deficiency in Switzerland (G6PD Avenches, G6PD I) and in Germany (G6PD Moosburg, G6PD II) are described. One patient had suffered from severe postpartal hyperbilirubinemia, the other one presented with chronic hemolysis and remittent hyperbilirubinemia. Both variants showed diminished electrophoretic mobility, both variants were heat labile. The Michaelis-Menten constants KM for glucose-6-phosphate and for NADP+ were normal. 2-Desoxy-glucose-6-phosphate was utilized by G6PD I in a higher and by G6PD II at a lower rate than by the normal enzyme. Desamino-NADP+ and galactose-6-phosphate were utilized by both variants at a normal rate. The electrophoretic separation of membrane proteins of G6PD II showed both in the presence and in the absence of 6-mercaptoethanol no difference concerning the formation of membrane protein aggregates between patient and normal control.     

G6PD lozere and trinacria-like

Summary Two new G6PD variants have been found in red blood cells of the members of a French family originating from Lozere. The father is hemizygous for an electrophoretically fast variant with mild enzyme deficiency (50–60% of normal). The abnormal paternal G6PD gene is segregating in his daughter who is double heterozygous for maternal and paternal variants. This mutant enzyme, different from previously described variants is designated as Gd Lozère. The mother is heterozygous for another G6PD variant. Two sons are hemizygous for this latter mutant enzyme characterized by a moderate deficiency (25–30% of normal) and slower electrophoretic mobility with some slightly altered kinetic properties. This G6PD has been identified as Gd Trinacria like.These two abnormal enzymes are not associated with any hemolytic problem. Case reported is the first showing the segregation of two new mutant enzymes, distinct from common G6PD variants, among the members of the same family.