HLA Polymorphisms Linked to the Severity and Extent of Periodontitis in Patients with Type 1 Diabetes from a Brazilian Mixed Population

This study aimed to investigate the relationship between Class II human leukocyte antigen (HLA) alleles (DRB1, DQA1, and DQB1) and the severity and extent of periodontitis in patients with Type 1 diabetes (T1D). A cross-sectional study was conducted with 49 patients with T1D. Demographic data and diabetes history were collected. A clinical examination was performed to assess periodontal variables. The patients were categorized by the periodontitis severity and the extent of periodontitis. Peripheral blood samples were analyzed to identify the percentage of autosomal ancestry (Native American, European, and African) and the HLA-DRB1*, HLA-DQA1*, and HLA-DQB1* alleles. The DRB1*03 and DRB1*15 haplogroups were significantly associated with an increased risk of generalized periodontitis (OR = 19.8, 95% CI = 1.14-346, <i>p</i> = 0.003; OR = 41.2, 95% CI = 1.85-917, <i>p</i> < 0.001) and severe periodontitis (OR = 7.7, 95% CI = 1.68-35.5, <i>p</i> = 0.003; OR = 21.2, 95% CI = 0.97-461, <i>p</i> = 0.005). No associations were observed between the HLA-DQA1 and HLA-DQB1 alleles and periodontitis. These findings suggest that patients with T1D from a highly mixed Brazilian population carrying the DRB1*03 and DRB1*15 haplogroups are at higher risk for developing more severe and generalized forms of periodontitis.