In summary, this work substantially advances the field of OCD genetics by identifying new OCD genetic risk loci and multiple credible candidate causal genes, including those expressed in brain regions and cell types previously implicated in OCD86. We have also shown that OCD is highly polygenic in nature, with many variants implicated not only in OCD but also in commonly comorbid disorders or traits, in particular, anxiety, neuroticism, anorexia nervosa and depression. The observation that common variants explain only a modest amount of the phenotypic variation in OCD suggests that other types of genetic variation may also contribute to the etiology of OCD. Notably, whole-exome-sequencing studies have suggested that a substantial proportion of OCD cases (22%) may be influenced by rare de novo coding variants87, especially in genes that are intolerant to loss of function88. Similarly, rare potentially damaging copy number variations represent part of the risk architecture for OCD9. These findings emphasize the need for a comprehensive exploration of the contribution of both common and rare genetic factors as well as their interplay to OCD risk. Finally, with the
