Cavernomas appear sporadically (1:200) or as an autosomal dominant (1:10,000) loss-of-function germline mutation of KRIT1 (CCM1), Malcavernin (CCM2), or PDCD10 (CCM3) in endothelial cells of the CNS [2,3]. The gene discussed is CCM2; the disease is cavernous hemangioma.