G6PD deficient alleles and haplotype analysis of human G6PD locus in São Tomé e Príncipe (West Africa).

A population sample from São Tomé e Príncipe (West Africa) was screened for the G6PD-deficient variants A- (376G/202A), Betica (376G/968C), and Santa Maria (376G/542T). G6PD locus haplotype diversity was also investigated using six intragenic RFLPs (FokI, PvuII, BspHI, PstI, BclI, NlaIII) and a (CTT)n microsatellite 18.61 kb within the G6PD locus. The estimated frequencies of the G6PD*B normal allele, the G6PD*A variant (376G), and the G6PD*A- allele were 0.698, 0.194, and 0.108, respectively. G6PD variants Betica and Santa Maria were not found. Similar levels of microsatellite diversity were found on variants G6PD*B and G6PD*A (H = 0.61 and 0.68, respectively), indicating a similar age for both alleles. All G6PD*A- alleles share the RFLP-microsatellite haplotype ++(-)+(-)+/195, the same haplotype described in nearly all the *A-alleles from sub-Saharan, Mexican Mestizo, and Portuguese populations, consistent with a single and recent origin of the G202A mutation on this *A haplotype.