Immune related genetic polymorphisms and schizophrenia among the Chinese

Genetic association studies were conducted among two independent cohorts of Chinese ethnicity. The samples consisted of cases and unrelated controls, ascertained from Guangzhou, China, and Singapore. The studies were prompted by our earlier report of an association between schizophrenia and HLA DQB1 alleles (HLA DQB1*0602 and HLA DQB1*0303) in the Singapore sample. Polymorphisms of HLA DQB1 and flanking markers on chromosome 6p21.3 were investigated in the first part of the study. A significant negative association with HLA DQB1*0402 was detected in the Guangzhou sample (Odds ratio, OR 0.26, 95% confidence intervals, CI 0.1, 0.6; p < 0.02, corrected for multiple comparisons). Additional analysis of the Guangzhou and Singapore samples revealed associations at three other anonymous markers flanking HLA DQB1. In the second part of the study, three polymorphisms at the Interleukin-1 gene cluster (IL-1, chromosome 2q13-q21) were investigated in both cohorts, since associations with schizophrenia have been reported in another sample. Persuasive evidence for an association at IL-1 was not detected in either sample. Our results suggest a susceptibility locus for schizophrenia in the HLA region among the Chinese, but further clarification is necessary.