Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pili annulati ?
    ### Response:
    Pili annulati is a hair disorder. In pili annulati, affected hair has a pattern of light and dark banding. People with pili annulati may describe their hair as "striped" or as having silvery beads. Pili annulati typically involves 20-80% of scalp hair, however it can involve facial and body hair as well.
    