CTLA-4 confers a risk of recurrent schizophrenia, major depressive disorder and bipolar disorder in the Chinese Han population

Previous studies have reported that the cytotoxic T lymphocyte antigen-4 (CTLA-4) gene, which is related to immunological function such as T-cell regulation, is associated with psychiatric disorders. In this study, we studied the relationship between CTLA-4 and three major psychiatric disorders, schizophrenia, major depressive disorder and bipolar disorder in the Chinese Han population. We recruited 1140 schizophrenia patients, 1140 major depressive disorder patients, 1140 bipolar disorder patients, and 1140 normal controls to examine the risk conferred by 6 tag SNPs (rs231777, rs231775, rs231779, rs3087243, rs5742909, rs16840252) in the CTLA-4 gene. We found that rs231779 conferred a risk for schizophrenia (P_allele = 0.0003, P_genotype = 0.0016), major depressive disorder (P_allele = 0.0006, P_genotype = 0.0026) and bipolar disorder (P_allele = 0.0004, P_genotype = 0.0018). In addition, rs231777 and rs16840252 had a significant association with schizophrenia (rs231777: P_allele = 0.0201, rs16840252: P_allele = 0.0081, P_genotype = 0.0117), and rs231777 had significant association with bipolar disorder (rs231777: P_allele = 0.0199). However, after 10,000 permutations, only rs231779 remained significant (schizophrenia: P_allele = 0.0010, P_genotype = 0.0145, major depressive disorder: P_allele = 0.0010, P_genotype = 0.0201, bipolar disorder: P_allele = 0.0008, P_genotype = 0.0125). Our results suggest that shared common risk factors for schizophrenia, major depressive disorder and bipolar disorder exist in the CTLA-4 gene in the Chinese Han population.