Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Refsum Disease ?
    ### Response:
    Adult Refsum disease (ARD) is a rare genetic disease that causes weakness or numbness of the hands and feet (peripheral neuropathy). Due to a genetic abnormality, people with ARD disease lack the enzyme in peroxisomes that break down phytanic acid, a type of fat found in certain foods.
    