Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to epidermal nevus ?
    ### Response:
    Mutations in the FGFR3 gene have been found in approximately 30 percent of people with a type of nevus in the keratinocytic epidermal nevi group. The gene mutations involved in most epidermal nevi are unknown.  Mutations associated with an epidermal nevus are present only in the cells of the nevus, not in the normal skin cells surrounding it.
    