Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) nail-patella syndrome ?
    ### Response:
    Nail-patella syndrome is characterized by abnormalities of the nails, knees, elbows, and pelvis. The features of nail-patella syndrome vary in severity between affected individuals, even among members of the same family.  Nail abnormalities are seen in almost all individuals with nail-patella syndrome.
    