Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) neurofibromatosis type 1 ?
    ### Response:
    Neurofibromatosis type 1 is a condition characterized by changes in skin coloring (pigmentation) and the growth of tumors along nerves in the skin, brain, and other parts of the body. The signs and symptoms of this condition vary widely among affected people.
    