OLIG2 gene polymorphisms are associated with nasty, unpleasant and uncontrollable thoughts in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) is one of 10 major debilitating neuropsychiatric disorders, according to the World Health Organization (WHO), affecting around 2.3% of people worldwide. Obsessive-compulsive symptoms are caused by shared or distinct genetic or environmental influences. Several imaging studies have detected white-matter alterations in OCD, and recent studies have demonstrated thatOCD is associated with variations in the OLIG2 gene. The aim of this study was to investigate whether OLIG2 gene is associated with OCD and its clinical features in a Brazilian sample. We genotyped three variants in OLIG2 gene, rs762178, rs1059004, and rs9653711 in 205 OCD patients and 202 healthy controls by Taqman® methodology. Genotypes and alleles distributions were analyzed by χ2 or Fisher exact tests. The rs762178 and rs9653711 polymorphisms were significantly associated with OCD (P = 0.048 and 0.029, respectively). We also observed an association of rs1059004 and rs9653711 with the presence of Obsessive-Compulsive Inventory-Revised (OCI-R) obsessing (unacceptable thoughts) subscore (P = 0.031 and 0.034, respectively). Moreover, the pair of loci consisting of rs762178 and rs9653711 A-G haplotype was associated with OCD (P < 0.0001). The OLIG2 gene may be involved in OCD, particularly in patients showing nasty, unpleasant and uncontrollable thoughts. However, more studies in larger samples are needed to replicate these findings.