CADASIL (also known as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is the most common cause of hereditary cerebral small-vessel disease and vascular cognitive impairment in young adults.

It is, as implied by the name, an autosomal dominant condition caused by a NOTCH3 mutation on chromosome 19.

Characteristically, this presents with a migraine with aura, and a family history of such, which can ultimately lead to stroke-like features and is a recognised important cause of stroke in the young. Brain imaging will reveal multiple subcortical white matter lesions, particularly in the anterior temporal lobes and basal ganglia, out of keeping with the patient's age.