Association between netrin G1 genetic variation and schizophrenia: a meta-analysis

Objective: Previous researches have reported that netrin G1 gene polymorphisms was associated with schizophrenia risk, but the results are inconsistent. Consequently, we implemented a meta-analysis to reveal the connection between the single nucleotide polymorphisms (SNPs) (rs1373336, rs2218404 and rs4132604) in NTNG1 gene and schizophrenia. Methods: Eligible case-control literatures that were published up to August 2016 were collected via searching PubMed, Cochrane Library, CNKI, Medline, Embase and Science Direct web of knowledge databases. Pooled odds ratio with 95% confidence interval were applied to access the strength of association in fixed-or random-effects model. Genotype distributions in the controls were tested for agreement with the Hardy-Weinberg equilibrium (HWE) using the X-2 test. Publication bias of the literature was evaluated by funnel plots and Begg's test. Results: The meta-analysis incorporated four eligible studies. There were 2,705 cases and 2,707 controls for SNP rs1373336, 2,723 cases and 2,770 controls for SNP rs2218404 and 1,371 cases and 1,382 controls for SNP rs4132604. This meta-analysis proved a significant association between rs4132604 and schizophrenia risk under dominant, OR 0.71, 95% CI 0.61-0.84, P=0.000; heterozygous, OR 0.72, 95% CI 0.61-0.85, P=0.000; homozygous, OR 0.70, 95% CI 0.57-0.87, P=0.001; and allelic, OR 0.82, 95% CI 0.74-0.91, P=0.000. However, no combination was found in the recessive model (OR: 0.86; 95% CI: 0.71-1.03, P=0.087). In addition, there was no significant association between rs1373336, rs2218404 and schizophrenia risk. Conclusion: This meta-analysis suggested that the SNP rs4132604 in NTNG1 gene might be responsible for schizophrenia susceptibility.