Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Moyamoya Disease ?
    ### Response:
    Moyamoya disease is a rare, progressive cerebrovascular disorder 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 tangle of tiny vessels formed to compensate for the blockage.
    