Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Urea cycle disorders ?
    ### Response:
    A urea cycle disorder is a genetic disorder that results in a deficiency of one of the six enzymes in the urea cycle. These enzymes are responsible for removing ammonia from the blood stream. The urea cycle involves a series of biochemical steps in which nitrogen, a waste product of protein metabolism, is changed to a compound called urea and removed from the blood.
    