ARFGEF2 and periventricular nodular heterotopia: Concerning the roles of Arfs in cortical development, mutations in human genes for ARF1 and its GEF, ARFGEF2, have been linked to periventricular nodular heterotopia, suggesting the involvement of Arf1 in cortical radial migration (Sheen et al., 2004; Gana et al., 2022).