KIF14 (OMIM ID: 611279) and CEP55 (OMIM ID: 610000), like CIT, are recessively inherited etiologies of microcephaly, whereas variants in PPP1R12A (OMIM ID: 602021) are responsible for a de novo dominant form of a holoprosencephaly spectrum that includes individuals with microcephaly (53–55). Here, PPP1R12A is linked to holoprosencephaly.