Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) pantothenate kinase-associated neurodegeneration ?
    ### Response:
    Pantothenate kinase-associated neurodegeneration (formerly called Hallervorden-Spatz syndrome) is a disorder of the nervous system. This condition is characterized by progressive difficulty with movement, typically beginning in childhood. Movement abnormalities include involuntary muscle spasms, rigidity, and trouble with walking that worsens over time.
    