Association analysis between IL-2Rβ gene polymorphism and myasthenia gravis

Objective To explore the association of three single nucleotide polymorphisms (SNPs; rs228942, rs228941 and rs743777) in interleukin-2 receptor β subunit (IL-2Rβ) gene with the susceptibility and severity of myasthenia gravis (MG). Methods There were 480 MG patients and 487 normal controls enrolled in this study, and their three SNPs (rs228942, rs228941 and rs743777) in IL - 2Rβ gene were evaluated through SNPscanTM technique. Subgroups were classified by gender, age of onset, anti - acetylcholine receptor antibodies (AChR-Ab), thymus status, maximal involvement after 2 years of onset and maximal Oosterhuis score. Frequencies of alleles and genotypes were compared between MG group and control group, between MG subgroups and control group, and among subgroups under codominant, log - additive and overdominant models. Results The frequency of T allele of rs228942 in MG group was significantly higher than that in control group (χ2 = 4.692, P = 0.030, OR = 1.242, 95%CI: 1.021-1.511). There was significant difference in the frequency of rs228942 genotype between MG group and control group under log-additive model (P = 0.036, OR = 1.230, 95%CI: 1.010-1.480). The rs278942/rs228941 GT haplotype frequency in MG group was higher than that in control group (χ2 = 4.286, P = 0.038), while GG haplotype frequency in MG group was lower than that in control group ( χ2 = 5.333, P = 0.021). The frequencies of T allele of rs228942 was significantly higher in MG subgroups of onset age 15-50 years (χ2 = 7.474, P = 0.006, OR = 1.380, 95%CI: 1.095-1.740), non-thymoma (χ2 = 4.700, P = 0.030, OR = 1.261, 95%CI: 1.022-1.555) and maximal generalized involvement ( χ2 = 4.715, P = 0.030, OR = 1.287, 95% CI:1.025-1.617) than those in control group. Multivariate forward Logistic regression analysis found that onset age 15-50 years (OR = 9.026, 95%CI: 4.225-19.284; P = 0.000), onset age > 50 years (OR = 9.956, 95%CI:4.475-22.149; P = 0.000), thymoma (OR = 2.578, 95%CI: 1.393-4.773; P = 0.003) and positive AChR-Ab (OR = 1.946, 95%CI: 1.179-3.214; P = 0.009) were the independent risk factors for maximal involvement, while genotypes were not. Conclusions The rs228942 polymorphisms of IL-2Rβ gene may be associated with the susceptibility of MG, but not with the severity of MG. The rs228941 and rs743777 polymorphisms were not found to be associated with the susceptibility and severity of MG. DOI: 10.3969/j.issn.1672-6731.2016.10.006