To model the hereditary and sporadic type of CCM disease in vitro (Figure 1), we used BOECs isolated from peripheral blood of a CCM proband with a heterozygous CCM1 loss-of-function germline variant (CCM1+/−) and wild-type CI-huVECs (CCM1+/+). The gene discussed is KRIT1; the disease is cerebral cavernous malformation.