KRIT1 and famililal cerebral cavernous malformations: KRIT1 was originally identified through a yeast two-hybrid screening designed to find interacting partners of the Ras-like GTPase Rap1 [1], and subsequently found to be one out of three genes responsible for causing Cerebral Cavernous Malformations (CCM; OMIM 116860) [2], [3], [4].