Polygenic inheritance does not preclude the possibility, perhaps strong, of rare variants with large effects. Such variants can only account for a tiny fraction of heritability in a population for the simple reason that they affect only a very small number of individuals. While we tested rare variants in the present work and found a few potential signals, this work was conducted with approximately one third the whole sample. Falling costs will permit studying larger samples, and additional studies in carefully selected samples will be required to further evaluate the contribution of rare variants in these endophenotypes.
