Objective: The functional polymorphism of interleukin (IL)-17F 7488 A > G was found to be associated with autoimmune inflammatory diseases and also high IL-17F intestinal expression in inflammatory bowel disease (IBD) was detected. The purpose of this study was to investigate the association between the polymorphism and IBD in the Chinese population and to elucidate potential interactions between IL-17F genotypes and clinical phenotypes.
Material and methods: DNA was extracted from peripheral blood cells of 148 ulcerative colitis (UC), 134 Crohn's disease (CD) patients and 373 age- and gender-matched healthy controls. The IL-17F 7488 A > G polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing.
Results: In UC patients, the homozygous GG genotype frequency was significantly lower than that in the controls (0.0% versus 3.8%, p=0.014); Compared to that of wild-type AA patients, the AG heterozygous carriers have a later onset (43.3+/-11.1 years versus 34.6+/-14.8 years, p = 0.012) and a significantly higher incidence of mild severity (94.1% versus 61.0%, p = 0.009, OR = 0.96, 95% CI = 0.94-0.96), respectively, indicating that subjects with the GG genotype have a slightly decreased risk of 0.96 times for UC compared with that of other genotypes. Further analysis also revealed that G carrier subjects were more likely to present mild severity and had 10.2 times higher incidence of getting mild severity than those with AA genotype (OR = 10.2, 95% CI = 1.3-81.0).
Conclusions: This study shows that IL-17F 7488 A > G polymorphism is associated with weak UC protection in the Chinese population. The clinical phenotypes of UC are also affected by this polymorphism.