Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Metachromatic Leukodystrophy ?
    ### Response:
    Metachromatic leukodystrophy (MLD) is one of a group of genetic disorders called the leukodystrophies, which are characterized by the toxic buildup of lipids (fatty materials such as oils and waxes) and other storage materials in cells in the white matter of the central nervous system and peripheral nerves.
    