Analysis of variations in the NAPG gene on chromosome 18p11 in bipolar disorder.

A number of studies have implicated the chromosome 18p11 region as a susceptibility region for bipolar disorder. The gene encoding gamma-SNAP (NAPG), one of three soluble N-ethylmaleimide-sensitive fusion (NSF)-attachment proteins (SNAPs), is located in the 18p11 region and is thought to play a role in cellular processes required for neurotransmission in the central nervous system. The purpose of this study is to investigate whether polymorphisms in the human NAPG gene contribute to the etiology of bipolar disorder. To test this hypothesis, we used a case-control design in which the genotype and allele frequencies for five single-nucleotide polymorphisms in the human NAPG gene were compared between individuals with a diagnosis of type I bipolar disorder (n=460) and control individuals (n=191). The genotype results indicate that three of the single-nucleotide polymorphisms in the NAPG gene, rs2290279 (P=0.027), rs495484 (P=0.044) and rs510110 (P=0.046), show a nominal, statistically significant association with bipolar disorder at the genotype frequency level. The results of this study suggest that polymorphisms in the human NAPG gene may represent risk factors for the development of bipolar disorder, but before such a role can be established, the results of this study must be confirmed in additional populations of bipolar disorder patients and controls.