Haplotypes and Haplogenotypes Analysis Revealed an Association between IL-22 Gene Variants and Visceral leishmaniasis among Iranian Population

Introduction and Objectives: Visceral leishmaniasis (VL) is an infectious disease caused by an intracellular protozoan belonging to Leishmaniagenus. Interleukin(IL)-22plays important roles in inflammatory responses, chemotaxis, regulation of cellular proliferation and tissue repair. Considering the importance of IL-22 in the protection against VL and the effect of IL-22 single nucleotide polymorphisms (SNP)on its function and production, this study aimed to investigate the probable association of IL-22 SNPs with VL.Materials and Methods: The study was carried out on 110 patients with VL, 102 patient’s families (family group) who lived in the same area as the patients, and 144 healthy individuals with positive leishmanin skin test (control group). Four SNPs at position rs2227501 A/T, rs2227503 A/G, rs2227513 A/G, rs1026786A/G of IL-22 were analyzed by polymerase chain reaction-restricted fragment length polymorphism (PCR– RFLP). Results: At position rs1026786 A/G, the AA genotype was significantly higher in the controls than in the patients (P=0.001). The AG genotype was significantly higher in the patients and their families than that in the controls (P=0.0001 and P=0.002, respectively). Additionally, the A allele was significantly higher in the controls than in the patients (P=0.013). At position rs2227503, the AG genotype was significantly higher in the controls than the family group (P=0.025). The haplotype TGAA was significantly higher in the family group, compared to patients and control groups (P=0.004 and P=0.023, respectively). The haplotypes TAAG, TGAG andhaplogenotype TAAA/TGAAwere significantly higher in the patient than in the controls (P=0.046, P=0.014 andP=0.013, respectively). Conclusion: The presence of A allele and AA genotype at the position rs1026786of IL-22can be considered as a protective factor for VL and in contrast, the inheritance of the haplotypes TAAG and TGAG and haplogenotypeTAAA/TGAA may increase the risk of susceptibility to VL.