Glucose-6-phosphate dehydrogenase (G6PD) electrophoretic variants and the PvuII polymorphism in Southern African populations

Summary Southern African Bantu-speaking negroid and San populations were examined with regard to the glucose-6-phosphate dehydrogenase (G6PD) PvuII restriction fragment length polymorphism (RFLP) showing alleles of 4kb and 1.6 kb, called Type 1 and Type 2, respectively. The standardized disequilibrium coefficient for the electrophoretic G6PD types and PvuII alleles in the Southern African population was 0.28. The molecular lesion causing the Gd^A mutation is the same in the San and Southern African negroid populations. Gd^A chromosomes are found in association with both the Type 1 and Type 2 alleles, whereas none of the 62 Gd^B chromosomes from the Southern African populations had the Type 2 allele. Five of the 44 Gd^B chromosomes studied in the American Black population had the Type 2 allele, indicating that the Gd^B allele in the two populations may have different origins. The presence of all 3 A^– deficiency mutations in the G6PD A gene, in a region where the ancestral population was thought to have predominantly G6PD B, may be explained by their origin in Africa after the divergence of the races.