CYP3A5*3, CYP3A4*1B and MDR1 C3435T Genotype Distributions in Ecuadorians

Polymorphisms in CYP3A genes, such as CYP3A5 and CYP3A4, as well as in the MDR1 gene, which encodes for P-glycoprotein, have been implicated as genetic markers in several disorders. Differences in the frequency distribution of the allelic variants CYP3A5*3, CYP3A4*1B, and MDR1 3435T have been demonstrated between distinct ethnic groups. In this study we examined the frequency of these allelic variants in 317 healthy Mestizo individuals from Ecuador and made comparisons with results reported in the literature. The genotypes were determined by PCR-RFLP. Allele and genotype differences were studied by chi-square test. The MDR1 T allele frequency was similar to that of Spaniard or Asian populations, which is consistent with the ethnic origin of Ecuadorian Mestizo individuals (Amerindian and Spaniard Caucasians). By contrast, the CYP3A5*3 allele frequency was significantly lower in Ecuadorians than in Spaniards and other white populations and higher than in Central Americans, Asians and blacks. CYP3A4*1B was more common in Ecuadorians than in Caucasian or Asian populations but less present than in blacks. The differences in the polymorphism found in this work should be considered in allele-disease association studies.