Loss of KRIT1 expression leads to the development of cerebral cavernous malformations (CCM) (Del Curling et al., 1991; Zabramski et al., 1994), abnormalities characterized by leaky, enlarged (‘cavernous’) microvascular lesions in the brain and other tissues (Chan et al., 2010; Clatterbuck, 2001; Revencu, 2006). This evidence concerns the gene KRIT1 and cerebral cavernous malformation.