Here we evaluate whether a substantial portion of the heritability of OCD traces to common variation, as it does for autism and schizophrenia, and characterize its frequency spectrum, which is directly relevant to evolutionary processes. For example, in an early study estimating heritability of OCD from common variation, results in Davis et al. (5) suggested that alleles with the highest frequencies, i.e., those with MAF > 0.3, account for the bulk of SNP-based heritability of OCD. Similar findings were reported using meta-analysis of data from OCGAS and Davis et al. (16). Such a strong pattern would suggest that OCD was under strong balancing selection.
