ABSTRACT
Interactions between multiple genes and environmental factors could be related to the pathogenesis of type 1 diabetes (T1D). The Brazilian population results from different historical miscegenation events, resulting in a highly diverse genetic pool. This study aimed to analyze the mtDNA of patients with T1D and to investigate whether there is a relationship between maternal ancestry, self-reported color and the presence of T1D. The mtDNA control region of 204 patients with T1D residing in three geographic regions of Brazil was sequenced following the International Society for Forensic Genetics (ISFG) recommendations. We obtained a frequency of Native American matrilineal origin (43.6%), African origin (38.2%), and European origin (18.1%). For self-declared color, 42.6% of the patients with diabetes reported that they were White, 50.9% were Brown, and 5.4% were Black. Finally, when we compared the self-declaration data with maternal ancestral origin, we found that for the self-declared White group, there was a greater percentage of haplogroups of Native American origin (50.6%); for the self-declared Black group, there was a greater percentage of African haplogroups (90.9%); and for the Brown group, there was a similar percentage of Native American and African haplogroups (42.3% and 45.2%, respectively). The Brazilian population with diabetic has a maternal heritage of more than 80% Native American and African origin, corroborating the country's colonization history.
ABSTRACT
BACKGROUND/OBJECTIVES: The primary aim of this study was to evaluate the prevalence of autoimmune diseases (AIDs) and its associated factors in an admixed Brazilian population of patients with type 1 diabetes (T1D). The secondary one was to determine the relationship between AIDs and the occurrence of diabetes-related chronic complications (DRCC). METHODS: This cross-sectional, nationwide survey was conducted in 13 public clinics in 11 Brazilian cities. Overall, 1,760 patients were included; 967 females (55.9%), 932 (54%) Caucasians, aged 29.9 ± 11.9 years, age at diagnosis 14.8 ± 8.9 years, diabetes duration 15.5 ± 9.3 years and 12.2 ± 3.8 years of school attendance. AIDs were retrieved from medical records or self-report and stratified as follows: absence of AIDs, only autoimmune thyroid disease (AITD), and other AIDs including the combination with AITD (hyper or hypothyroidism). RESULTS: The prevalence of AIDs was 19.5% being AITDs (16.1%), the most frequently found. A higher prevalence of hypertension, dyslipidemia and overweight or obesity was found in patients who had exclusively AITDs. A higher prevalence of diabetic retinopathy (DR) was observed in patients with AITDs and patients with other AIDs in combination with AITDs. Chronic kidney disease (CKD) was more prevalent in patients with only AITDs. Lower levels of HbA1C, were observed in patients with isolated AITDs or with other AIDs, regardless of the presence of AITD. Hierarchical multivariate analysis, showed that AIDs were associated with female gender, older age, and longer diabetes duration, self-reported color-race (White and Brown), geographic region (Brazilian North/Northeast region) and higher anti-TPO levels (≥ 35 UI/ml). CONCLUSIONS: In conclusion, Brazilian patients with T1D, belonging to a highly ethnically admixed population, had an important prevalence of AIDs, mostly AITDs, that was associated with female gender, self-reported color-race, older age and longer diabetes duration. Moreover, these patients also had a higher prevalence of DRCC. Even though we highlight the importance of investigating the presence of AIDs at diagnosis and at regular intervals, it is unclear whether screening and early detection of additional AIDs may improve the clinical outcomes in individuals with T1D. Future prospective studies are necessary to establish the interplay between T1D, AIDs and DRCC.
