HLA class II polymorphisms and recurrent spontaneous abortion in a Southern Brazilian cohort.

A high proportion of human recurrent spontaneous abortions (RSA) remain unexplained. The possible association between RSA and different genetic polymorphisms within the human leucocyte antigen system (HLA system, the human major histocompatibility complex) has been investigated with conflicting results since many decades. Here, we describe a case-control study with 136 Southern Brazilian women of predominantly European ancestry (75 control and 61 cases with unexplained RSA). We investigated the relationship between unexplained RSA and alleles and genotypes from two classical loci of the HLA: HLA-DRB1 and HLA-DQB1, as well as three loci related to cytokine production and their serum levels: TNFA (-308G>A), IL10 (-1082G>A, -819T>C, -592A>C) and IFNG (+874A>T). Genotyping was performed by an allele-specific PCR method. While all results concerning cytokine-related genes turned out to be negative, we found the genotype HLA-DQB1*02:02, 03:01 to be significantly decreased and the allele HLA-DRB1*11:04 to be significantly increased among patients.

HLA polymorphism and evaluation of European, African, and Amerindian contribution to the white and mulatto populations from Paraná, Brazil.

Polymorphism of classical HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ genes differs greatly among populations, both in frequencies and in the presence of alleles and haplotypes particular to population groups, making these genes powerful tools for the study of origins of populations and their degree of admixture. Antigen, allele, and haplotype frequencies, together with linkage disequilibrium patterns, are reported for 2 populations in the southern Brazilian state of Paraná, one of predominantly European ancestry (white), the other of predominantly African and European ancestry (mulatto). Genetic distance estimates between the 2 groups and other populations studied previously, and of degree of admixture, were performed. In accordance with phenotypic classification, the white population is of predominantly European origin (80.6%), with a smaller contribution of African (12.5%) and Amerindian (7.0%) genes. The mulatto population consists of African (49.5%) and European (41.8%) ancestry, with a smaller but significant contribution of Amerindian (8.7%) ancestry. On the basis of history and population genetics, there is controversy regarding the Amerindian contribution to Paraná's gene pool. These results provide a better picture of Paraná's ethnic constitution and on the Amerindian contribution to the white and mulatto populations.