Mutations in the NOTCH3 gene cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) amd migraine.20,21 As a synonymous polymorphism, 684 G>A is thought to be non functional and does not alter coding sequences. This evidence concerns the gene NOTCH3 and cerebral arteriopathy with subcortical infarcts and leukoencephalopathy.