While not rising to the level of a high-confidence risk gene in this study, it is notable that we identified an OCD de novo damaging (Mis-D) variant in DLGAP1 (discs, large homolog-associated protein 1). In a genome-wide association study by the International OCD Foundation Genetic Collaborative (IOCDF-GC), the lowest p-values for their case-control analysis were found for two SNPs located within DLGAP1 (2.49×10−6, 3.44×10−6) (20). A subsequent GWAS by the OCD Collaborative Genetics Study (OCGAS) identified a SNP nearby this gene with a prominent signal (p=2.67×10−4) (18). Furthermore, a rare paternally-inherited duplication in DLGAP1 was recently reported in a child with OCD, Tourette syndrome, and anxiety (64). DLGAP1 is a member of the neuronal postsynaptic density complex and is in the same family as DLGAP3 (SAPAP3), a gene associated with OCD-like behaviors in a knockout mouse model (65). Therefore, evidence is beginning to converge on this gene as one of great interest in OCD genetics.
