Distribution of HLA class II alleles and haplotypes in Mexican Mestizo population: comparison with other populations.

We describe the analysis of the Major Histocompatibility Complex (MHC) class II polymorphism in Mexican Mestizo population. The study provides the HLA-DRB1, DQA1 and DQB1 allele frequencies in 99 Mexican Mestizos. DNA from these individuals was typed by PCR followed by hybridization using sequence specific oligonucleotides (PCR-SSO). The relationship with other worldwide populations was studied by using HLA data from 69 different populations and calculating neighbor-joining dendrograms and correspondence multidimensional values. The highest frequencies were for DRB10802 (allele frequency = 0.151), DRB10701 (allele frequency = 0.111) and DRB10407 (allele frequency = 0.106). Among the eight DQA1 alleles detected, the most frequent were DQA103011 (allele frequency = 0.257), DQA10501 (allele frequency = 0.227) and DQA10401 (allele frequency = 0.166). Twelve DQB1 alleles were found and four of them, DQB10302 (allele frequency = 0.237), DQB10301 (allele frequency = 0.176), DQB10201 (allele frequency = 0.166) and DQB10402 (allele frequency = 0.166) showed the highest frequencies. The haplotype DRB10802-DQA10401-DQB10402 (0.151) predominated clearly, followed by DRB10701-DQA10201-DQB10201 (0.111) and DRB10407-DQA103011-DQB1*0302 (0.101). Both genetic distances and correspondence analyses showed that Mexicans clustered with Amerindian population. These results suggest that the Mexican Mestizo population be principally characterized by haplotypes presents in Amerindian and Caucasian populations with a low frequency of Black haplotypes. In summary, the HLA class II haplotype frequencies demonstrated the tri-racial component existing in Mexican Mestizos.