ARFGEF2 and nodular neuronal heterotopia: Other ARFGEF2 mutations have been linked to autosomal recessive periventricular heterotopia with microcephaly (ARPHM), a rare disorder involving cerebral malformations, severe developmental delay, and recurrent pulmonary infections, whereas loss‐of‐function experiments implicated the gene in neuronal proliferation and migration (Sheen et al, 2004).