analysis of βS and βA Genes in a Mexican Population with African Roots

To investigate the origin of the βA and βS genes in a Mexican population with African roots and a high frequency of hemoglobin S, we analyzed 467 individuals (288 unrelated) from different towns in the states of Guerrero and Oaxaca in the Costa Chica region. The frequency of the sickle-cell trait was 12.8%, which may represent a public health problem. The frequencies of the β-haplotypes were determined from 350 nonrelated chromosomes (313 βA and 37 βS). We observed 15 different βA haplotypes, the most common of which were haplotypes 1 (48.9%), 2 (13.4%), and 3 (13.4%). The calculation of pairwise distributions and Neiʹs genetic distance analysis using 32 worldwide populations showed that the βA genes are more closely related to those of Mexican Mestizos and North Africans. Bantu and Benin haplotypes and haplotype 9 were related to the βS genes, with frequencies of 78.8, 18.2, and 3.0%, respectively. Comparison of these haplotypes with 17 other populations revealed a high similitude with the population of the Central African Republic. These data suggest distinct origins for the βA and βS genes in Mexican individuals from the Costa Chica region.