Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Moyamoya disease ?
    ### Response:
    Moyamoya disease is a rare, progressive, blood vessel disease caused by blocked arteries at the base of the brain in an area called the basal ganglia. The name "moyamoya" means "puff of smoke" in Japanese and describes the look of the tangled vessels that form to compensate for the blockage.
    