CADASIL or CADASIL syndrome, involving cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, is the most common form of hereditary stroke disorder, and is thought to be caused by mutations of the Notch 3 gene on chromosome 19. The disease belongs to a family of disorders called the leukodystrophies. The most common clinical manifestations are migraine headaches and transient ischemic attacks or strokes, which usually occur between 40 and 50 years of age, although MRI is able to detect signs of the disease years prior to clinical manifestation of disease. The condition was identified and named by French researchers Marie-Germaine Bousser and Elisabeth Tournier-Lasserve in the 1990s. Together with two other researchers, Hugues Chabriat and Anne Joutel, they received the 2019 Brain Prize for their research into the condition. Signs and symptoms CADASIL may start with attacks of migraine with aura or subcortical transient ischemic attacks or strokes, or mood disorders between 35 and 55 years of age. The disease progresses to subcortical dementia associated with pseudobulbar palsy and urinary incontinence. Ischemic strokes are the most frequent presentation of CADASIL, with approximately 85% of symptomatic individuals developing transient ischemic attacks or stroke(s). The mean age of onset of ischemic episodes is approximately 46 years (range 30–70). A classic lacunar syndrome occurs in at least two-thirds of affected patients while hemispheric strokes are much less common. It is worthy of note that ischemic strokes typically occur in the absence of traditional cardiovascular risk factors. Recurrent silent strokes, with or without clinical strokes, often lead to cognitive decline and overt subcortical dementia. A case of CADASIL presenting as schizophreniform organic psychosis has been reported. Pathophysiology The underlying pathology of CADASIL is progressive hypertrophy of the smooth muscle cells in blood vessels. Autosomal dominant mutations in the Notch 3 gene (on the long arm of chromosome 19) cause an abnormal accumulation of Notch 3 at the cytoplasmic membrane of vascular smooth muscle cells both in cerebral and extracerebral vessels, seen as granular osmiophilic deposits on electron microscopy. Leukoencephalopathy follows. Depending on the nature and position of each mutation, a consensus significant loss of betasheet structure of the Notch3 protein has been predicted using in silico analysis. Diagnosis MRIs show hypointensities on T1-weighted images and hyperintensities on T2-weighted images, usually multiple confluent white matter lesions of various sizes, are characteristic. These lesions are concentrated around the basal ganglia, peri-ventricular white matter, and the