Family6,7 and twin studies7 consistently support a genetic contribution to OCD. Heritability estimates of OCD, as well as obsessive-compulsive characteristics, indicate that genetic factors explain between 27% and 47% of the phenotypic variance7–10. Candidate gene association studies point to the glutamate transporter gene SLC1A111–15 and the glutamate receptor genes GRIN2B16,17 and GRIK218–20. Furthermore, genome-wide association studies (GWAS), though underpowered, converge on excitatory synaptic signaling as a potential source of dysfunction21–23.
