Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes 47, XYY syndrome ?
    ### Response:
    What causes 47, XYY syndrome? 47,XYY syndrome is caused by the presence of an extra copy of the Y chromosome in each of a male's cells. This is typically due to a random event during the formation of a sperm cell in the father, usually before conception (fertilization of the egg).
    