High prevalence of cytochrome P450 2A6*1A alleles in a black African population of Ghana

Objective: We investigated the frequencies of the functionally important variants of the CYP2A6 gene in black African populations. Methods: Using genomic DNA sequencing, polymerase chain reaction (PCR)-restriction fragment length polymorphism and allele-specific PCR, the allele frequencies of CYP2A6 *1A, *1B, *2, *4A, *5, *6, *7, *8, *9, *10 and *11 among 120 black Africans' including 105 Ghanaians, 12 Nigerians, 2 Ivorians and 1 Ugandan-were determined. Results: The allele frequencies were 80.5% for CYP2A6*1A, 11.9% for CYP2A6*1B, 1.9% for CYP2A6*4A and 5.7% for CYP2A6*9 in the Ghanaian subjects. No subject homozygous for the CYP2A6*4A allele, a whole gene deletion type of polymorphism prevalent among Orientals, was found. Furthermore, CYP2A6 variants such as *2, *5, *6, *7, *8, *10 and *11 were absent in these black African populations. Conclusions: This study provides, for the first time, the results of the analysis of CYP2A6 allele frequency in black African populations and confirms large ethnic differences in the polymorphic CYP2A6 gene.