Familial forms of CCM have been linked to loss-of-function mutations in genes encoding the proteins Krev interaction trapped protein 1 (KRIT1)/CCM1 (Laberge-le Couteulx et al, 1999), Malcavernin/CCM2 (Liquori et al, 2003), or programmed cell death 10 (PDCD10)/CCM3 (Bergametti et al, 2005). The gene discussed is CCM2; the disease is cerebral cavernous malformation.