Apolipoprotein E polymorphism in the Indian and Mestizo populations of Mexico.

Apolipoprotein E (APOE) genotypes were determined in 75 Mazatecan Indians and 83 Mexican mestizos. APOE allele and genotype frequencies in Mazatecans and mestizos were similar, with high frequencies of the APOE3 allele (0.900 and 0.915, respectively) and the E3/3 genotype (0.813 and 0.831, respectively) and an absence in both samples of the APOE2 allele. Our data are similar to those previously described for Mexican-American and Mayan populations, which show the highest frequency worldwide of the APOE3 allele and the E3/3 genotype. Mazatecans and mestizos also show a decreased frequency of the APOE4 allele when compared to other Amerindian groups. The absence of the APOE2 allele has also been reported in other Amerindian groups such as Mayans and Cayapa, whereas in Caucasians the average frequency of this allele is about 8%. Our data are in agreement with previous reports showing absence of the APOE2 allele in Native American groups. These findings suggest that the APOE*2 allele was absent in humans from northern Asia who settled in the Arctic and populated the American continent.