Analysis of PTPN22 C1858T gene polymorphism in cases with type 1 diabetes of Azerbaijan, Northwest Iran

Background: Type 1 diabetes (T1D) is a T-cell mediated autoimmune multifactorial disease. The PTPN22 gene encodes an intracellular lymphoid-specific phosphatase (Lyp) that has been shown to play a negative regulatory role in T cell activation.

Objectives: The aim of the present study was to find out associating the PTPN22 C1858T (R620W) polymorphism and T1D in the Azeri population from Northwest Iran.

Subjects and methods: One hundred and forty-four T1D patients and 197 healthy controls entered this study. We used restricted fragment length polymorphism (RFLP) method to type PTPN22 C1858T polymorphism.

Results: There was no significant difference in distribution of genotype and allele frequencies of PTPN22 C1858T polymorphism between T1D patients and controls (P=1.000 for both comparisons and OR=0.91, 95% CI=0.25-3.26 for 1858T allele). However, T allele frequency was significantly increased in T1D patients with Hashimoto's thyroiditis (5.77%) compared with T1D only (0.43%, P=0.019). Moreover, there were no significant differences between studied parameters (including gender, age at onset and family history of T1D) and different genotypes of 1858 PTPN22 C/T polymorphisms in patients. Data showed a low frequency of the minor (T) allele by 1.4% in T1D and 1.5% in healthy individuals.

Conclusions: The PTPN22 C1858T is not relevant in susceptibility to T1D in the Azeri population of Northwest Iran. Our data also indicate that T1D carriers of the T1858 allele could be at enhanced risk for other comorbid autoimmune disorders.