CADASIL: a Common Form of Hereditary Arteriopathy Causing Brain Infarcts and Dementia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebrovascular disease leading to cognitive decline and dementia. CADASIL usually begins with migraine in about one third of the patients. More severe manifestations, transient ischemic attacks or recurrent strokes, appear between 30 and 50 years of age. CADASIL, however, may be diagnosed well before the first stroke on the basis of characteristic white matter hyperintensities upon magnetic resonance imaging and presence of pathognomonic granular osmiophilic material in arterial walls, including dermal arteries, since the arteriopathy is generalized. Gradual destruction of vascular smooth muscle cells (VSMC) leads to progressive wall thickening and fibrosis and luminal narrowing in small and medium-sized penetrating arteries. The reduced cerebral blood flow finally causes lacunar infarcts, mainly in the basal ganglia and fronto-temporal white matter, which lead to cognitive deficits and dementia of the subcortical vascular type. CADASIL is caused by single missense mutations or small deletions in Notch3 gene encoding a transmembrane receptor Notch3, of which upon ligand binding a nuclear signaling protein is generated by regulated intramembrane proteolysis. Notch signaling is essential during development, regulating cellular differentiation. In adults Notch3 is expressed only in VSMCs and it may promote cell survival by inhibiting apoptosis, but its exact function is unknown. Mutations result in either a gain or loss of one (or rarely, 3) cysteine residue(s) in one of the 34 epidermal growth factor-like repeats in the extracellular amino-terminal region of Notch3. It is as yet unclear which disturbance in the Notch signaling pathway leads to the characteristic vascular pathology of CADASIL.