Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to X-linked severe combined immunodeficiency ?
    ### Response:
    Mutations in the IL2RG gene cause X-linked SCID. The IL2RG gene provides instructions for making a protein that is critical for normal immune system function. This protein is necessary for the growth and maturation of developing immune system cells called lymphocytes.
    