In cancer, pathogenic ARID1A mutations affect subunits of the SWI/SNF complex inducing a disruption in phosphatase and tensin homolog (PTEN) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIKC3A) signaling, thus aberrant expression of these genes could lead to brain malformations, as both PTEN and PIKC3A haploinsufficiency have been linked to ventriculomegaly/hydrocephalus [48]. The gene discussed is PIK3CA; the disease is cancer.