The loss of function (LOF) mutations of CCM1 (KRIT1, Krev interaction trapped protein 1) (23–27), CCM2 (MGC6407, encoding a protein named malcavernin) (28–33), and CCM3 (PDCD10, Programmed cell death protein 10) (34–36) have been thought to be the culprits of familial CCM. Here, KRIT1 is linked to cerebral cavernous malformation.