Particular emphasis was placed on the study of mutations in the Notch3 protein and the structure analysis of the mutant Notch3 protein that leads to the manifestation of the CADASIL syndrome in order to spot possible conserved mutations and interpret the effect of these mutations in the Notch3 protein structure. This evidence concerns the gene NOTCH3 and cerebral arteriopathy, autosomal dominant, with subcortical infarcts and leukoencephalopathy, type 1.