Association of interleukin-17F gene polymorphism with enterovirus 71 encephalitis in patients with hand, foot, and mouth disease.

Enterovirus 71 (EV71) is one of the common pathogenic agents of hand, foot, and mouth disease (HFMD) and is associated with severe complications including encephalitis. Interleukin (IL)-17F plays an important role in tissue inflammation by inducing release of proinflammatory cytokines and chemokines. We investigated the association between EV71 encephalitis and of IL-17F 7488T/C (rs763780) gene polymorphism, which is known to cause a His-to-Arg substitution at amino acid 161. The study was performed in 58 Chinese patients with EV71 encephalitis and 127 Chinese patients with EV71-related HFMD without complications. Genotyping was determined by the polymerase chain reaction-restriction fragment length polymorphism technique. The patients with EV71 encephalitis had a significantly lower frequency of the IL-17F 7488TC+CC genotypes (10.3%) as compared to the patients with EV71-related HFMD without complications (27.6%, p = 0.008). The frequency of IL-17F 7488C alleles was also significantly lower among the patients with EV71 encephalitis (5.2%) as compared to that of the patients with EV71-related HFMD without complications (15%, OR = 0.310, 95% CI = 0.127-0.756, p = 0.006). Furthermore, homozygotes with the T allele had significantly higher levels of C-reactive protein, white blood cell count, and neutrophil count as compared to the patients with CC+CT genotypes (p = 0.004, 0.001, and 0.000, respectively). These findings suggested that the IL-17F 7488C allele could be significantly associated with protection against encephalitis in Chinese patients with EV71-related HFMD.