IL-1A rs1800587, IL-1B rs1143634 and IL-1R1 rs2234650 polymorphisms in Iranian patients with systemic sclerosis

Systemic Sclerosis (SSc) is a systemic autoimmune disorder, with ambiguous pathogenesis. Genetic and environmental factors were proved to be correlated with SSc aetiology. Single nucleotide polymorphisms (SNPs) in cytokine genes can alter the structure and function of the cytokines and consequently may increase the susceptibility to a specific disease. In this study, we investigated SNPs of the IL-1 gene cluster in Iranian SSc patients. We obtained blood samples from 170 SSc patients and 213 healthy individuals. Cytokine genotyping results were obtained by polymerase chain reaction with sequence-specific primers (PCR-SSP). IL-1A rs1800587, IL-1B rs1143634 and IL-1R1 rs2234650 were evaluated for SNP study. The frequency of the IL-1B rs1143634 CT genotype was significantly lower in SSc patients compared to the controls (OR = 0.584; 95% CI = 0.385-0.886; P-value = 0.023), so we propose that CT genotype of this allele might be protective. According to our haplotype analysis, CCC haplotype frequency is higher in the control group compared to SSc patients (OR = 1.575; 95% CI = 1.176-2.111; P-value = 0.008) and in contrast, CTC haplotype frequency is lower in the control group compared to SSc patients (OR = 0.152; 95% CI = 0.047-0.484; P-value = 0.002), so they might decrease and increase the susceptibility of having SSc, respectively. In addition, we reported two significant diplotypes frequency differences among SSc patients and healthy individuals. It is highly important that there is not much resemblance between the IL-1 gene cluster polymorphism in different populations, so we can indicate that SNPs may play critical roles when they are combined with other genetic and environmental factors.