In addition to advances in understanding regarding familiality and genetic mechanisms that are likely to be involved in OCD, there have also been dramatic gains in our understanding of the phenotype of OCD. Perhaps most important for genetic research are new ways to assess the phenotype dimensionally, moving beyond traditional categorical diagnostic classifications. Over the last decade, results from a number of independent studies have demonstrated that there are different clusters of symptoms that comprise the OCD phenotype73-77 and that they appear to be heritable.73,76 It follows then that there may be several genes that could influence the different components of OCD.
