Investigation of DNA repair genes in patients with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a major psychiatric disorder identified mostly by obsessions and compulsions. Molecular genetic and gene-expression studies focused on familial and twin cases have shown a wide variety of variant genes related to OCD.

The aim of the study was to investigate DNA repair genes as potential molecular markers in OCD by evaluating the distribution of polymorphisms of DNA repair genes in OCD patients.

The study included 100 case subjects with OCD and 122 unrelated healthy controls. Genotyping of XRCC1, XRCC3, XPD, XPG, APE1 and HOGG1 was performed by polymerase chain reactionrestriction fragment length polymorphism.

Significant differences were found for XPD and genotype frequencies. Likewise, the frequency of the XPD Lys+ genotype was significantly increased in the patients as compared to the controls, and carriers of the Lys+ genotype had an increased risk for OCD (p = 0.027). The XPD Lys/Lys genotype frequency was also increased in the patients in comparison to the controls (p < 0.001). XPD Gln+ frequencies were higher in the controls than in the patients, and carriers of the Gln+ genotype showed decreased levels of OCD risk (p < 0.001). XPD Lys/Lys genotype frequency and XPD Gln+ frequency are also significantly associated even after Bonferroni correction (p < 0.008).

The findings suggest that XPD Lys/Lys might play a facilitating role in the development of OCD.