CCM2 and cerebrocostomandibular syndrome: Besides sporadic cases, about 6–7 % of CCMs occur in a familial form that is inherited in an autosomal dominant manner and caused by loss-of-function germline variants in CCM1 (KRIT1; OMIM: *604214), CCM2 (OMIM: *607929), or CCM3 (PDCD10; OMIM: *609118) [3], [4].