KAT5 and orofacial cleft: On the basis of the findings presented in this study, it is reasonable to assume that the early defects in the survival and expansion of the cranial neural crest are also at least in part causative for the syndromic orofacial clefts observed in patients with heterozygous Kat5 mutations and may also explain the role of Kat5 as a quantitative trait locus in non-syndromic forms.13,14