HLA Genotypes and Type 1 Diabetes and Its Relationship to Reported Race/Skin Color in Their Relatives: A Brazilian...

Area of Science:

• Immunogenetics
• Population Genetics
• Endocrinology

Background:

• Type 1 diabetes (T1D) is an autoimmune disease with a complex genetic basis.
• Admixed populations, like Brazilians, present challenges in determining the ancestral origins of disease-associated genes.
• Human Leukocyte Antigen (HLA) genes are critical in autoimmune diseases, including T1D.

Purpose of the Study:

• To investigate the association between HLA alleles in Brazilian patients with T1D and the reported race/skin color of their relatives.
• To explore the potential European ancestry of T1D-associated genotypes in an admixed population.

Main Methods:

• Cross-sectional, multicenter study in nine Brazilian cities involving 662 T1D patients and their relatives.
• Collection of demographic data, race/skin color, and birthplace information for relatives.
• HLA-DRB1, -DQA1, and -DQB1 gene typing.

Main Results:

• Most patients (95.17%) reported having at least one White relative.
• The most frequent HLA allele observed was DRB1*03:01, often associated with European ancestry.
• Increased odds of the DRB1*03:01 allele were found in patients reporting exclusively White relatives.

Conclusions:

• The findings suggest a probable European origin for the T1D genotype in the Brazilian population.
• The prevalence of the European-derived DRB1*03:01 allele supports this conclusion.
• Further research using diverse ancestry markers is necessary to fully elucidate the genetic origins of T1D in admixed populations.