Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) 47, XYY syndrome ?
    ### Response:
    47, XYY syndrome is a condition in males characterized by features that occur due to having an extra copy of the Y chromosome in each cell. Signs and symptoms can vary and range from barely noticeable to more severe; many men with the extra Y chromosome are completely unaware of its presence.
    