Of the 10 genes found to harbor an exome-wide significant excess of rare damaging coding mutations in schizophrenia in the SCHEMA Consortium analysis (17), TRIO is known to play an important role in developmental neurite outgrowth (46), while Setd1a haploinsufficiency in mice has been reported to reduce axonal branching (47) and SP4 knockdown to affect dendritic branching (48) during development. Here, SP4 is linked to schizophrenia.