Influence of admixture components on CYP2C9*2 allele frequency in eight indigenous populations from Northwest Mexico

Abstract

We previously documented the lowest frequency of CYP2C9*2 in Mexican indigenous Tepehuanos followed by Mestizos and Mexican-Americans populations, suggesting a negative correlation between the CYP2C9*2 frequency and the degree of Asian ancestry in indigenous Americans. We determined the influence of ethnic admixture components on the CYP2C9 allele distribution in 505 Amerindian from eight indigenous populations through genotyping CYP2C9*2, *3 and *6 alleles by real-time PCR and molecular evaluation of ancestry. The frequencies for CYP2C9*2 were 0.026 in Seris and 0.057 in Mayos, being higher than in Asians (P<0.001). CYP2C9*3 was found in Tarahumaras (0.104), Mayos (0.091), Tepehuanos (0.075), Guarijíos (0.067), Huicholes (0.033) and Coras (0.037), with East Asians having lower frequencies than the former three groups (P<0.001). CYP2C9*6 was not found. The frequency of CYP2C9*2 was lower in Amerindians than in European populations, and higher than their Asian ancestors. The presence of this allele in ethnic groups in Mexico can be explained by European admixture.

Present status and perspective of pharmacogenetics in Mexico

“…A high frequency of variant *2 was found in Tarahumaras (Table 1), and a *2/*2 genotype of 10.7%, which means a potentially poor metabolizer group. Furthermore, these frequencies are different from those reported for Guadalajara Mestizos [18].…”

“…Genotype *1/*3 was found in six of the studied samples [Tarahumara (20.27%), Mayo (18.18%), Tepehuano (11.81%), Guarijio (13.33%), Huichol (6.54%), Cora (7.41%)]. Variant *6 was not found [18].…”

“…In Seri (5.26%) and Mayo (11.36%) samples, genotype *1/*2 was more frequent when compared with the other samples, whereas homozygous genotype variant *2 was not found [18].…”

“…The most recent collaboration dates from 2013: a report on CYP2C9 in eight indigenous populations from Northwestern Mexico [18].…”

“…In 2013, Sosa et al reported that genotype *1/*1 was present in 100% of the Mexicanero sample [18], and it also was the most frequent in Seri (94.74%), Huichol (93%), Cora (92.59%), Guarijio (86.67%), and Tepehuano (86.61%) samples. Genotype *1/*2 was found only in two of the eight samples [Seri (5.26%) and Mayo (11.36%)], at higher frequencies than those reported in Asian populations.…”