[Influence of alleles and haplotypes of the main histocompatibility complex on the susceptibility to systemic lupus erythematosus in the Mexican population].

HLA alelles with susceptibility to systemic lupus erythematosus (SLE) have been found in many ethnic groups. In addition, some neighboring genes such as TNF-alpha and HSP70, that may contribute to this disease have also been described. Interestingly some of the genetic associations differ among several ethnic groups, which might suggest that ethnicity plays an important role in the predisposition to SLE. In this study, we analyze gene frequencies of HLA-DRB1, DQA1, DQB1, HSP70-2 alelles and the polymorphism of TNF-alpha promoter region among 81 Mexican mestizo SLE patients. A control group of 99 healthy Mexican mestizos was included. We found that the HLA-DRB1*0301-DQA1*0501-DQB1*0201 haplotype was significantly increased in SLE patients compared to healthy controls (p=0.01, OR=2.97, IC 95%=1.18-7.68). The DRB1*1501 allele was more frequent among patients than among controls. A significantly decreased frequency of the HLA-DRB1*0802 alelle in SLE patients was also observed. Since the HLA alelles associated with SLE are uncommon in Mexican ethnic groups, we performed admixture estimates analysis and found that the incorporation of SLE susceptibility markers in Mexican mestizo groups might have come from genetic admixture with Caucasian populations.