KRIT1 and cerebral cavernous malformation: Familial CCM is an autosomic dominant genetic disorder caused by loss‐of‐function mutations in anyone of three genes, namely Ccm1 (Krit1), Ccm2 (Osm), and Ccm3 (Pdcd10) (Laberge‐le Couteulx et al, 1999; Bergametti et al, 2005; Labauge et al, 2007; Riant et al, 2013).