Investigation of the Relationship between PTPN22 Polymorphisms and Lung Sarcoidosis: A cross sectional study

Objective: Sarcoidosis is a systemic granulomatous disease with an unknown etiology characterized by noncaseating granuloma formation. It most often affects the lungs. Protein tyrosine phosphatase non-receptor 22 (PTPN22) is a gene that acts as a negative regulator of T-cell activation. Polymorphisms of this gene are associated with multiple human autoimmune diseases. The aim of this study was to assess the relationship between PTPN22 polymorphisms and lung sarcoidosis in a selected population. Methods: The study included 64 patients with lung sarcoidosis and 30 healthy controls. Patients were genotyped to determine two single nucleotide polymorphisms (SNPs) using the polymerase chain reaction (PCR) method. Hardy–Weinberg equilibrium (HWE), an important tool for detecting genotyping errors, was tested. Direct counting was used to estimate genotype frequencies. Logistic regression analysis was performed to compare allele and genotype frequencies between the patient and control groups. Results: The results of the study showed no correlation between lung sarcoidosis and the tested two SNPs of the PTPN22 gene (rs2488457, rs1310182) (p>0.05). The categorization analysis according to the clinical features, laboratory, and radiographic characteristics showed no correlation between the tested polymorphism of PTPN22 and these characteristics (p>0.05). Conclusion: The present study demonstrated that the studied two SNPs of the PTPN22 gene (rs2488457, rs1310182) were not correlated with lung sarcoidosis, suggesting that it might be different from other classic autoimmune disorders. There is a need for more studies to verify these results concerning lung sarcoidosis in other ethnic origins.