TAP2 polymorphisms in Iranian patients with type I diabetes mellitus

Type I diabetes (T1D) is an immune mediated disease characterized by immune destruction of insulin producing pancreatic beta cells. This disease is associated with the human major histocompatibility complex (HLA) region of the genome. The presentation of self peptides by HLA class I molecules is defective in individuals with this disease and both TAP1 and TAP2 are potential contributors to this defect. The aim of this study was to identify the correlation between TAP2 polymorphisms and T1D in Iran. Five known coding regions of TAP2 gene (sites 379, 565, 651, 665 and 687) were typed in a case-control study of 87 Iranian patients with T1D and 104 control subjects by using the amplification refractory mutation system (ARMS) PCR technique. The polymorphisms examined in codon 379 and 687 differed in frequencies between patients and controls and there is not any significant difference in frequencies between diabetic patients and control subjects in other three examined sites. TAP2 A was the most frequent allele in Iranian subjects (51.9% in healthy subjects and 47.1% in diabetic patients). The next frequent alleles in our subjects were TAP2 G and B and the frequencies of other alleles (TAP2 C, D, E and F) were usually lesser than 10%. TAP2 D allele was not present in our population and TAP2 E allele was not present in our diabetic patients. In conclusion, the polymorphisms examined in codon 379 and 687 differed in frequencies between patients and controls. We can consider these polymorphisms in all suspected individuals with diabetes under 30 years old.