Introduction: Schizophrenia has a strong genetic basis. It is reported that the matrix metalloproteinase-9 (MMP-9) -1562C/T polymorphism (rs3918242) may be associated with schizophrenia; however, current evidences are conflicting. Methods: A systematic literature search was conducted on PubMed and Web of Science to identify all the available evidences of the association of schizophrenia with rs3918242 polymorphism. Baseline information and genotype distribution were extracted from eligible study for quantitative data synthesis. Odds ratio (OR) and 95% confidence interval (95% CI) were used to estimate the effect size. Quality assessment was performed for each study using Newcastle-Ottawa Scale (NOS). Results: Four eligible studies were included in this study. Data synthesis indicated that rs3918242 polymorphism was not associated with schizophrenia (OR = 1.04, 95% CI = 0.69-1.58), with high heterogeneity (I2 = 75%, p = .007). No publication bias was visually observed according to funnel plot. Sensitivity analysis showed a significant association (OR = 1.29, 95% CI = 1.03-1.63) when a specific study was removed. Conclusions: MMP-9 rs3918242 polymorphism may not be associated with schizophrenia. Given a crucial role of MMP-9 molecule on the pathogenesis of schizophrenia, this result should be verified by more studies with scientifically rigorous design and large population.
Keywords: Schizophrenia; matrix metalloproteinase; meta-analysis; polymorphism.