Allele and Genotype Frequencies of Cytochrome P450 2B6 516G>T Single Nucleotide Polymorphism in HIV-Negative and HIV-Infected Adult Nigerian Populations.

Polymorphisms in genes have been found in most enzymes involved in drug metabolism, especially in the cytochrome P450 (CYP) family with considerable ethnic differences in their frequencies. Single nucleotide polymorphisms (SNPs) are the major source of these genetic variations. CYP2B6 516G>T SNP found in both CYP2B6*6 and CYP2B6*9 alleles significantly reduces CYP2B6 protein expression and enzyme activity with important implications on the pharmacokinetics and pharmacodynamic outcomes of some clinically relevant drug substrates. This study determined the frequencies of CYP2B6 516G>T SNP in HIV-negative and HIV-infected adult Nigerian populations. Three hundred unrelated subjects (150 each of HIV-negative volunteers and HIV-infected patients) of different Nigerian ethnic groups residing in Ilorin and Ile-Ife and its environs, respectively, were recruited and genotyped for their CYP2B6 516G>T genetic status using real-time polymerase chain reaction. Differences in allele and genotype frequencies between both populations were tested using Pearson χ test. Minor allele frequency of 36.4% and genotype frequencies of 38.7% GG, 50.0% GT, 11.3% TT and a minor allele frequency of 37.0% and genotype frequencies of 42.0% GG, 42.0% GT, 16.0% TT were obtained for the HIV-negative volunteers and HIV-infected patients, respectively. χ test indicated a significant relationship between genotype frequencies in both populations (P < 0.001). The minor allele and genotype frequencies obtained in the 2 populations significantly differ and corroborate previous studies, which have reported CYP2B6 516G>T SNP in various other African populations.