In adult onset, the evidence indicates a somewhat, lower estimate, ranging from 27% to 47%. OC symptom dimensions have rarely been evaluated in the context of twin studies, with the one exception

being a recent study by van Grootheest. et al90 In this study, data from a population sample Inhibitors,research,lifescience,medical of 1383 female twins from the Virginia Twin Registry was examined OC symptoms were measured by a self-report questionnaire with 20 items from the Padua Inventory. Investigators found that each of the OC symptom dimensions shared variation with a latent common factor. Variation in this common factor was explained by both genes Inhibitors,research,lifescience,medical (36%) and environmental factors (64%). In their data only the Contamination dimension appeared to be influenced

by specific genes. Like many other psychiatric disorders, family and affected sibling studies also suggest, that genetic factors play Inhibitors,research,lifescience,medical a role in the expression of OCD. Alsobrook and colleagues91 were the first to use OC symptom dimensions in a familygenetic study. They found that, the relatives of OCD Ponatinib Bcr-Abl probands who had high scores on the obsessions/checking and symmetry/thereby ordering factors were at greater risk for OCD than were relatives of probands who had low scores on those factors. The finding that relatives of OCD probands who had high scores on symmetry/ordering were at greater risk for OCD than were relatives of probands who had low scores has been replicated in a second independent family study.92 Using Inhibitors,research,lifescience,medical data collected by the Tourette Inhibitors,research,lifescience,medical Syndrome Association International Consortium for Genetics

Affected Sibling Pair Study, Leckman and colleagues93 selected all available affected TS pairs and their parents for which these OC symptom dimensions Anacetrapib (factor scores) could be generated using the four-factor algorithm. Remarkably, 50% of the siblings with TS were found to have comorbid tic-related OCD and >30% of mothers and 10% of fathers also had a diagnosis of OCD. The scores for both Factor I (aggressive, sexual, and religious obsessions and checking compulsions) and Factor II (symmetry and ordering) were significantly correlated in sibling pairs concordant, for TS. In addition, the motherchild correlations, but. not father-child correlations, were significant for these two factors. Based on the results of the complex segregation analyses, significant evidence for genetic transmission was obtained for all factors.