Correlation between CTLA4 genetic polymorphisms, its serum protein level and the susceptibility to recurrent spontaneous abortion: A case–control study

Present study was aimed to detect the influence of cytotoxic T-lymphocyte associated protein 4 (CTLA4) gene polymorphisms for the risk of recurrent spontaneous abortion (RSA), as well as the serum level of CTLA4 protein in RSA patients. One hundred thirty-three RSA patients and 146 healthy persons were recruited in this case–control study. PCR-RFLP was used to genotype the CTLA4 gene polymorphisms both in case and control groups. Serum level of CTLA4 was detected by ELISA kit. Quantitative variables were compared by t test or Mann–Whitney U test between groups. Qualitative variables were evaluated by χ(2) test or Fisher exact test. Association strength was expressed by odds ratios (ORs) and 95% confidence intervals (95% CIs). G allele of rs4553808 (P = .027, OR = 0.570, 95% CI = 0.345–0.942) and T allele of rs5742909 (P = .027, OR = 0.570, 95% CI = 0.345–0.942) were distinctly associated with reduced susceptibility of RSA. Distinctly negative association has been discovered between rs231775 AA genotype and RSA susceptibility (P = .040, OR = 0.427, 95% CI = 0.188–0.973). CTLA4 protein had significantly higher serum level in RSA patients than in healthy controls (P = .028). In RSA patients, AA genotype carriers had higher CTLA4 serum level than that GG genotype carriers (17.83 ± 6.35 ng/mL vs 10.41 ± 7.28 ng/mL, P = .039). Minor alleles of CTLA4 polymorphisms might inhibit the RSA susceptibility via upregulated the protein expression level.