Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Infantile Refsum Disease ?
    ### Response:
    Infantile Refsum disease (IRD) is a medical condition within the Zellweger spectrum of perixisome biogenesis disorders (PBDs), inherited genetic disorders that damage the white matter of the brain and affect motor movements. PBDs are part of a larger group of disorders called the leukodystrophies.
    