Cytotoxic T lymphocyte-associated antigen-4 gene promoter polymorphisms in patients with systemic lupus erythematosus in southern Chinese population

Purpose To assess the association between polymorphisms within Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) gene promoter and the morbidity of systemic lupus erythematosus (SLE) in Chinese people. Methods A case-control led study was performed for CTLA-4 polymorphisms, -1722 T)C and -318 C)T in the promoter region in 97 patients with SLE and 200 healthy individuals. We examined the CTLA-4 genotype of these subjects by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results There was a significant difference in -1722 T)C genotype frequencies between the two groups (P = 0. 002). Carrier frequencies of the -1722 T allele in the promoter were significantly increased in SLE patients compared with those in con-trois (odds ratio= 1. 94, 95% confidence interval: 1. 34 - 2. 80, P = 0. 000). There was no difference in -318 C)T genetype and allele frequencies between the two groups. However, there was a linkage disequilibrium between the -1722 T)C and -318 C)T. There was a significant difference in CTLA-4 haplotype distribution between the two groups (χ² = 12.64, P = 0. 005) , which the relative high proportion was T-C haplotype (P = 0. 001) and the less one was C-C haplotype (P = 0. 002) in SLE group, compared to control group. Conclusions The -1722 T)C in the promoter of CTLA-4 was determined to be susceptible to SLE in southern Chinese population. Although the result showed that -318 C)T was not responsible for SLE, the T-C haplotype might be a susceptible haplotype and C-C haplotype a protective one in southern Chinese population.