Abstract

GENETIC POLYMORPHISM IN PROTEIN TYROSINE PHOSPHATASE NON-RECEPTOR 22 (PTPN22) GENE IN IRAQI PATIENTS WITH RHEUMATOID ARTHRITIS

Ahmed Yaseen AL-Tarboolii*, Hameed Majeed Jassim, Mohammed Hadi Alosami, Saleh Ahmed Wohaieb

Abstract

Rheumatoid arthritis (RA) is a common autoimmune disease characterized by chronic inflammation and joint destruction. The aim of the present study was to investigate the genetic polymorphism (rs2746601) for the gene encoding protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene in Iraqi RA patients. A total of 35 samples (25 RA patients and 10 healthy controls) were recruited in this study. Genetic polymorphism in Protein Tyrosine Phosphatase non-receptor 22 (PTPN22) was studied for rs2476601 SNP in exon 14 within chromosome 1. This SNP (rs2476601) was regarded as a major risk factor associated with susceptibility and severity of rheumatoid arthritis. Genomic DNA was first extracted from blood samples for healthy controls and treated RA patients. Results showed that the concentration of extracted DNA ranged between 100-200 ng/μl with purity of 1.8-2.0. Then exon 14 was amplified by using specific primers designed in this study. Results of amplification showed a single band of 684bp was obtained after electrophoresis on agarose gel (1.8%) which represents the complete nucleotide sequence of exon 14. To examine genetic polymorphism (rs2476601) in this exon, the nucleotide sequence for this fragment was determined. Results showed that the rs2476601 SNP was non-polymorphic in both RA patients and healthy control subjects with total absence of the variant ‘T’ allele. Furthermore, the frequency of the ‘T’ allele was 0.0, with T/T, C/T and C/C genotype frequencies of 0.0, 0.0, and 1.0, respectively. In conclusion, this study shows that the rs2476601 SNP of the PTPN22 gene is non-polymorphic in Iraqi population and therefore not associated with RA. However, since variations in the rest of the gene were not investigated, these results do not exclude other PTPN22 polymorphisms from playing a role in RA susceptibility in Iraq.

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