Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) CADASIL ?
    ### Response:
    CADASIL (Cerebral Autosomal Dominant Arteriopathy with Sub-cortical Infarcts and Leukoencephalopathy) is an inherited disease of the blood vessels that occurs when the thickening of blood vessel walls blocks the flow of blood to the brain. The disease primarily affects the small blood vessels in the white matter of the brain.
    