The most significant SNP rs78587207 (P = 5.28 × 10−12) identified in the GWAS is located on chr11q12.1 and has been previously associated with several traits, including neuropsychiatric phenotypes39 such as depressive symptoms40 and neuroticism40. Gene-based analyses identified four putative causal genes within this locus. The closest gene to rs78587207 is catenin delta 1 (CTNND1), which encodes the cell adhesion molecule p120-catenin. This gene was associated with OCD using three gene-based tests (mBAT-combo, TWAS, and PWAS) and we found strong evidence for colocalization of the TWAS signal for CTNND1 in dorso-lateral prefrontal cortex (dlPFC). dlPFC has been consistently implicated in the neural circuitry of OCD as well as in compulsivity more broadly as part of the cortico-striatal-thalamo-cortical circuitry41,42. The protein product of CTNND1 is a regulator of cell-cell adhesion43 and plays a crucial role in gene transcription, Rho GTPase activity, and cytoskeletal organization44–46. Other credible causal genes in the locus include cleavage factor polyribonucleotide kinase subunit 1 (CLP1), thioredoxin related transmembrane protein 2 (TMX2), and zinc finger DHHC-type palmitoyltransferase 5 (ZDHHC5). Rare genetic mutations in CLP1 are associated with pontocerebellar
