OBJECTIVEThe genomic region of the human major histocompatibility complex (MHC) is located in the short arm of chromosome 6 (6p). Linkage studies have shown that the 6p region may contain a gene for schizophrenia, the MHC region has thus become particularly important in searching for the schizophrenia susceptibility gene. The present study was designed to investigate the genetic association of DRB3 and DRB1 genes with psychotic symptoms of schizophrenia.

METHODSPCR-based restriction fragment length polymorphism (RFLP) analysis was applied to genotype two single nucleotide polymorphisms (SNPs) located in the DRB3 locus and in the DRB1 one in 116 Chinese Han family trios consisting of fathers, mothers and affected offspring with schizophrenia. Chi-square (chi(2)) test and haplotype-based relative risk (HRR) analysis were used on genotyping data.

RESULTSData on HRR analysis did not show a genetic association either between the DRB3 locus and schizophrenia or between the DRB1 locus and the illness. However, the SNP rs707954, a G to T base change, present in the DRB1 locus showed strong association with idea of reference (chi(2) = 5.484, df = 1, P = 0.019), while the genotype of rs707954 showed an association with idea of reference (chi(2) = 6.771, df = 2, P = 0.034) as will as with apathy (chi(2) = 12.110, df = 4, P = 0.017).

CONCLUSIONDRB1 locus seemed likely to be associated with psychotic symptoms as idea of reference and apathy. Further studies were necessary to reveal the relations between DRB1 gene or nearby locus with its susceptibility to schizophrenia.