HTRA1 and CARASIL: Where patients have no known identifiable NOTCH3 mutation, they can also be categorised as being CADASIL-like and if a genetic cause is found could be re-classified as a similar condition (e.g. HTRA1 mutations in cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) or GLA mutations in Fabry disease) [28, 29].