Positive association between synapsin II and schizophrenia

Background Synapsin II encodes a neuron-specific phosphoprotein that selectively binds to small synaptic vesicles in the presynaptic nerve terminal. The expressions of messenger ribonucleic acid and protein of synapsin II have been reported to be significantly reduced in the brains of schizophrenia patients. The synapsin II gene is located on 3p25, a region that has been implicated to be associated with schizophrenia by genetic linkage. All these findings suggest synapsin II as a candidate gene for schizophrenia. Methods In this work, we studied four markers (two single nucleotide polymorphisms (SNPs): rs308963 and rs795009; and two insertion/deletion polymorphisms: rs2307981 and rs2308169) covering 144.2 kilobase pairs (kb) with an average interval of 38 kb in synapsin II in a sample of 654 schizophrenic patients and 628 normal control subjects to explore the mechanism underlying schizophrenia. Results We found significant differences in allele frequency distribution of SNP rs795009 (p = .000018, odds ratio 1.405, 95% confidence interval 1.202-1.641) between patients and control subjects. The T allele was significantly higher in patients than in control subjects. Moreover, the overall frequency of haplotype showed significant differences between patients and control subjects (p< .000001). Conclusions This study suggests a positive association between synaspin II and schizophrenia, implying that synapsin II is involved in the etiology of schizophrenia.