Cytotoxic T lymphocyte antigen-4 (CTLA-4) rs231775 and rs5792909 polymorphisms are not associated with adult- and childhood-onset type 1 diabetes in a Southern Brazilian population
Several studies have described an association between cytotoxic T-lymphocyte antigen-4 (CTLA-4) gene polymorphism and type 1 diabetes mellitus (T1D) in some ethnic populations, and a lack of association in other populations. Differences in the contribution of the genetic background of T1D onset are age dependent. We conducted a case-control study of a T1D Brazilian population, in which a possible association of rs231775 (+49A/G) and rs5792909 (-318C/T) polymorphisms in CTLA-4 with T1D was evaluated. These polymorphisms were genotyped in 150 childhood-onset (age £ 14 years old) and 150 adult-onset (age >18 years) patients with diabetes and non-diabetic healthy individuals (150 children and 150 adults). PCR-restriction fragment length polymorphism (rs5792909) and TaqMan® fluorescent probe (rs231775) methodologies were used for genotyping. The polymorphisms were in Hardy-Weinberg equilibrium. There was no difference in genotype and allele frequency between the patients with T1D and non-diabetic controls. The frequencies for childhood-T1D and adulthood-T1D, for the rs231775 G-allele (95% CI) were 39.0% (31–47) and 37.3% (30–46), and for the T-allele of the rs5792909 polymorphism they were 5.0% (3–7%) and 2.7% (1–4%), respectively. We did not identify an association of CTLA-4 rs231775 and rs5742909 polymorphisms with adult- or childhood-onset T1D in a Euro-Brazilian population in Southern Brazil.