Polymorphism V362F (rs2304256) of tyrosine kinase 2 is not associated with childhood- or adulthood-onset type 1 diabetes in southern Brazil
Type 1 diabetes mellitus (T1D) is considered a polygenic disease that is influenced by environmental factors and autoimmune responses to autoantibodies, resulting in metabolic abnormalities. Tyrosine kinase 2 (TYK2) is involved in type I interferon signaling in beta cells, and TYK2 polymorphism rs2304256 has been associated with T1D. We investigated polymorphism rs2304256 (TYK2) in a case-control study of Euro-Brazilians with T1D manifested during childhood and adulthood. We studied 307 individuals manifesting clinical signs of type 1 diabetes (151 children below 14 years of age and 156 adults with diagnosis after 18 years of age). The control samples consisted of 169 healthy children and 150 healthy adult subjects. T1D groups had inadequate glycemic control because fasting glucose and mean HbA1C concentrations were significantly higher than in the control groups. Real-time PCR with TaqMan® fluorescent probes was applied for genotyping. The studied polymorphisms were in Hardy–Weinberg equilibrium. The minor allele frequency (A-allele) for children in the T1D and control groups was 24.2% (95% CI, 18 - 32) and 23.4% (95% CI, 17 - 30), respectively (P = 0.812), while for adults in the T1D and control groups values were 19.6% (95% CI, 14 - 27) and 24.7% (95% CI, 20 - 35), respectively (P = 0.127). There was no significant difference in genotypes or allelic frequencies of the polymorphism in the groups. The frequency of the minor allele of the polymorphism was similar to that found in other Caucasian populations, and different than that found in Eastern populations. In conclusion, the polymorphism rs2304256 was not associated with T1D in either group.