Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pantothenate kinase-associated neurodegeneration ?
    ### Response:
    Pantothenate kinase-associated neurodegeneration (PKAN) is a rare, movement disorder characterized by a progressive degeneration of the nervous system (neurodegenerative disorder). PKAN is generally separated into classic and atypical forms. Children with classic PKAN develop symptoms in the first ten years of life.
    