Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to narcolepsy ?
    ### Response:
    Narcolepsy probably results from a combination of genetic and environmental factors, some of which have been identified, but many of which remain unknown.  In most cases of narcolepsy with cataplexy, and in some cases without cataplexy, sleep abnormalities result from a loss of particular brain cells (neurons) in a part of the brain called the hypothalamus.
    