Frequência dos alelos HLA-DRB1 e HLA-DQB1 na população brasileira

Abstract

The Human Leukocyte Antigen (HLA) system is essential for the regulation of the adaptive immune system and is composed of a set of highly polymorphic genes located on chromosome 6. It is observed that some alleles of the HLA-DRB1 and HLA-DQB1 genes are frequently found together in a greater proportion than expected based on their location on the chromosome. This phenomenon called linkage disequilibrium occurs between the DR and DQ genes and allows the typing of one of the alleles to be inferred based on the allele of the other gene observed using gene association tables. The present essay sought to evaluate the allelic frequencies of the HLA-DRB1 and HLA-DQB1 genes from REDOME samples in the states of Paraná, Amazonas and Distrito Federal from the Immunogenetics Laboratory of Hospital Cajuru in Curitiba, as well as construct an association table between these genes to assist the clinical process of typing for solid organ transplantation and contrast the frequencies obtained with the DR-DQ association tables currently used, and their possible clinical impact on solid organ transplantation. Frequency analyzes and haplotype inference were conducted in the Arlequin 3.5 program and principal component analysis (PCA) with “FactoMineR” and “factoextra” packages in R. The most frequent alleles in the entire set of samples were DRB1* 07:01:01 (13.26%), DRB1*15:01:01 (7.95%), DRB1*13:01:01 (7.60%) and DQB1*05:01:01 (14. 81%), DQB1*02:02:01 (11.60%), DQB1*03:02:01 (11.03%). Analysis of allele and haplotype frequencies demonstrated that Brazilian populations present a large mixture of HLA alleles and common haplotypes of white, african and native american populations, with the geographic factor determining the distribution of alleles in the country. Frequency comparisons were not useful, demonstrating the need to seek applicable alternatives for effective comparison of alleles of complex and highly polymorphic genes such as HLA.