Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Klippel Feil syndrome ?
    ### Response:
    Klippel Feil syndrome (KFS) is a congenital, musculoskeletal condition characterized by the fusion of at least two vertebrae of the neck. Common symptoms include a short neck, low hairline at the back of the head, and restricted mobility of the upper spine.
    