Genetic association studies in obsessive-compulsive disorder

Background: Obsessive-compulsive disorder (OCD) segregates in families. It follows a complex model of genetic transmission, which involves the influence of several small effect genes interacting with the environment. Methods: A systematic review of genetic association studies in OCD was performed. Articles published until 2012 were searched in the databases PubMed, Embase and SciELO using the terms of MeSH and its associates or synonyms for "obsessive-compulsive disorder", "gene" and "genetic association studies". Results: We selected 105 papers and described their main results grouped as genes related to: serotonin, dopamine, glutamate, GABA, white matter, immune system, hormones and other genes. Conclusion: There is high variability between findings of association studies among the several candidate genes studied in OCD. Glutamate-related genes are promising candidates for OCD, but there is no conclusive association between any of the candidate genes studied and OCD. Association studies with large sample size, evaluation of more homogeneous subgroups of phenotype and meta-analyses are still needed.