Genetic polymorphism of cytochrome P450 CYP2D6 in Zimbabwean population

The objective of this study was to determine the CYP2D6 genotype of a black Zimbabwean population. Genotyping was carried out using Eco RI and Xba I RFLP, and allele-specific PCR amplification. Of 114 Zimbabwean samples analysed, no individual homozygous for any of the defect allelic forms CYP2D6A, CYP2D6B or CYP2D6D or combinations thereof was found. The allele frequencies of the three defect genes were 0, 1.8 and 3.9%, respectively. No subject carrying the Xba I 44 kb haplotype, indicative for poor metabolizers among Caucasians, was identified, whereas five individuals being heterozygous with a 29/42 kb haplotype were seen. Three out of the four CYP2D6B alleles found were associated with the 29/42 kb haplotype. Our findings are in agreement with the 0-2% prevalence of poor metabolizers (PMs) in the black populations previously phenotyped. The very low frequency of the CYP2D6B allele in the Zimbabwean population is different from very recent data from black Americans (allele frequency = 8.5%) and might indicate the Caucasian ancestry of this allele. Taken together, our data indicate important interethnic differences in the CYP2D locus between Caucasian, Asian and different black populations.