Association study of polymorphisms in synaptic vesicle-associated genes, SYN2 and CPLX2, with schizophrenia

BACKGROUND: The occurrence of aberrant functional connectivity in the neuronal circuit is one of the integrative theories of the etiology of schizophrenia. Previous studies have reported that the protein and mRNA levels of the synapsin 2 (SYN2) and complexin 2 (CPLX2) genes were decreased in patients with schizophrenia. Synapsin 2 and complexin 2 are involved in synaptogenesis and the modulation of neurotransmitter release. This report presents a study of the association of polymorphisms of SYN2 and CPLX2 with schizophrenia in the Korean population. METHODS: Six single nucleotide polymorphisms (SNPs) and one 5-bp insertion/deletion in SYN2 and five SNPs in CPLX2 were genotyped in 154 Korean patients with schizophrenia and 133 control patients using direct sequencing or restriction fragment length polymorphism analysis. An intermarker linkage disequilibrium map was constructed for each gene. RESULTS: Although there was no significant difference in the genotypic distributions and allelic frequencies of either SYN2 or CPLX2 polymorphisms between the schizophrenia and control groups, the two-way haplotype analyses revealed significant associations with the disease (P < 0.05 after Bonferroni correction). The three-way haplotype analyses also revealed a significant association of SYN2 with schizophrenia (P < 0.001 after Bonferroni correction). CONCLUSION: These results suggest that both SYN2 and CPLX2 may confer susceptibility to schizophrenia in the Korean population.