Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is one of the most common hereditary cerebral small vessel diseases caused by mutations in NOTCH3. C was first recognized as a clinical and genetic hereditary small-vessel disease entity that induces cerebral infarction, white matter (WM) disease, microbleeds, and finally, vascular dementia. The gene discussed is NOTCH3; the disease is CADASIL.