Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to X-linked agammaglobulinemia ?
    ### Response:
    Mutations in the BTK gene cause XLA. This gene provides instructions for making the BTK protein, which is important for the development of B cells and normal functioning of the immune system. Most mutations in the BTK gene prevent the production of any BTK protein.
    