ELECTROPHORETIC HETEROGENEITY OF GLUCOSE-6-PHOSPHATE DEHYDROGEN ASE AND ITS RELATIONSHIP TO ENZYME DEFICIENCY IN MAN

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Abstract
Several electrophoretic variants or glucose-6-phosphate dehydrogenase are recognizable among Negro subjects in the absence of enzyme deficiency. Such variation is present in both erythrocytic and leukocytic enzyme and is not accompanied by alteration in other enzymatic properties. Leukocytic enzyme provides a convenient source of material for typing subjects with erythrocytic G-6-PD deficiency. Limitation of the heterozygous class to females suggests that the responsible structural locus is X-linked. Population and family studies support this conclusion but also indicate that additional factors may influence phenotype. The association of a particular G-6-PD variant, type A, with enzyme deficiency in all but one of 63 G-6-PD-deficient Negro males suggests that the locus controlling deficiency and the structural locus are closely linked. Evidence from population studies suggests that the distance between loci is not greater than two map units. Since no recombination between loci has been observed, it is possible that the two loci are part of the same functional unit. In contrast to Negroes, Greek G-6-PD-deficient subjects possess electrophoretic phenotype B. The B phenotype is the only type observed in Americans of European origin. One subject with congenital nonspherocytic hemolytic anemia presented a unique electrophoretic pattern, thus supporting the view that structural alteration of G-6-PD can produce this disorder.