Abstract
This study aimed to investigate the relationship between genetic ancestry inferred from autosomal and Y chromosome markers and HLA genotypes in patients with Type 1 Diabetes from an admixed Brazilian population. Inference of autosomal ancestry; HLA-DRB1, -DQA1 and -DQB1 typifications; and Y chromosome analysis were performed. European autosomal ancestry was about 50%, followed by approximately 25% of African and Native American. The European Y chromosome was predominant. The HLA-DRB1*03 and DRB1*04 alleles presented risk association with T1D. When the Y chromosome was European, DRB1*03 and DRB1*04 homozygote and DRB1*03/DRB1*04 heterozygote genotypes were the most frequent. The results suggest that individuals from Maranhão have a European origin as their major component; and are patrilineal with greater frequency from the R1b haplogroup. The predominance of the HLA-DRB1*03 and DRB1*04 alleles conferring greater risk in our population and being more frequently related to the ancestry of the European Y chromosome suggests that in our population, the risk of T1D can be transmitted by European ancestors of our process miscegenation. However, the Y sample sizes of Africans and Native Americans were small, and further research should be conducted with large mixed sample sizes to clarify this possible association.
Highlights
This study aimed to investigate the relationship between genetic ancestry inferred from autosomal and Y chromosome markers and histocompatibility leukocyte antigen system (HLA) genotypes in patients with Type 1 Diabetes from an admixed Brazilian population
Type 1 Diabetes (T1D) is a disorder of glucose homeostasis, which develops as a result of the synergistic effects of genetic, immunological, and environmental factors that lead to the loss of β cell secretory function[1,2]
Our study showed that individuals with and without T1D from a highly admixed population in Maranhão, a northeastern state of Brazil, have a higher European ancestry
Summary
This study aimed to investigate the relationship between genetic ancestry inferred from autosomal and Y chromosome markers and HLA genotypes in patients with Type 1 Diabetes from an admixed Brazilian population. The predominance of the HLA-DRB1*03 and DRB1*04 alleles conferring greater risk in our population and being more frequently related to the ancestry of the European Y chromosome suggests that in our population, the risk of T1D can be transmitted by European ancestors of our process miscegenation. In patients of African origin, additional haplotypes are associated with risk, such as DRB1*09:01 ~ DQA1*03:01 ~ DQB1*02:0 1 and DRB1*07:01 ~ DQA1*03:01 ~ DQB1*02:018. It is important to note that same haplotype, such as DR7 molecule, is often seen in Europeans with a protective effect and as a risk factor in African-American populations. The non-recombining portion of the Y chromosome (NRY) does not undergo recombination with the X chromosome during meiosis and is transmitted practically intact through the paternal strains as h aplotypes[14]; the evaluations of their polymorphisms being useful for ancestral population a nalyzes[15]
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