Association study of bromodomain-containing 1 gene with schizophrenia in Japanese population

Chromosome 22q13 region has been implicated in schizophrenia in several linkage studies. Genes within this locus are therefore promising genetic and biologic candidate genes for schizophrenia if they are expressed in the brain or predicted to have some role in brain development. A recent study reported that bromodomain-containing 1 gene (BRD1), located in 22q13, showed an association with schizophrenia in a Scottish population. Except for being a putative regulator of transcription, the precise function of BRD1 is not clear; however, expression analysis of BRD1 mRNA revealed widespread expression in mammalian brains. In our study, we explored the association of BRD1 with schizophrenia in a Japanese population (626 cases and 770 controls). In this association analysis, we first examined 10 directly genotyped single-nucleotide polymorphisms (SNPs) and 20 imputed SNPs. Second, we compared the BRD1 mRNA levels between cases and controls using lymphoblastoid cell lines (LCLs) derived from29 cases and 30 controls. Although the SNP (rs138880) that previously has been associated with schizophrenia showed the same trend in the Japanese population, no significant association was detected between BRD1 and schizophrenia in our study. Similarly, no significant differences in BRD1 mRNA levels in LCLs were detected. Taken together, we could not strongly show that common SNPs in the BRD1 gene account for a substantial proportion of the genetic risk for schizophrenia in the Japanese population.