MHC microsatellites in a Southern Brazilian population

Microsatellites are short tandem repeats of 1-6 bp DNA fragments, which are found throughout the genome. Due to their high levels of polymorphism, many of them are used as markers for population studies. Here we report an investigation on four microsatellites (D6S273, D6S2792, STR_MICA and D6S2810) located within the major histocompatibility complex in a sample of 281 Southern Brazilians of European ancestry. Allelic and haplotypic frequencies are described, as well as linkage disequilibrium (LD) between alleles of these microsatellites and alleles of three HLA genes: HLA-B, HLA-DRB1 and HLA-DQB1. The most polymorphic microsatellite was D6S2810, located close to the HLA-B locus. Strong LD was observed between alleles of microsatellites and HLA genes. The strongest associations occurred among STR_MICA*A5.1-HLA-B*13, STR_MICA*A6-HLA-B*49, STR_MICA*A9-HLA-B*39, STR_MICA*A9-HLAB*57, D6S2810*334-HLA-B*14, D6S2810*334-HLA-B*38, STR_MICA*A5.1-HLA-DRB1*1501-HLA-DQB1*0602 and D6S2810*344-HLA-DRB1*0411-HLA-DQB1*0302. This study contributes with important information on HLA haplotypes, and is potentially useful in resolving cases of low resolution HLA genotyping ambiguities.