Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Proud syndrome ?
    ### Response:
    What causes Proud syndrome? Proud syndrome is caused by changes (mutations) in the ARX gene, which encodes a protein that regulates the activity of other genes. This protein is especially important during early embryonic development since it is thought to be involved in the formation of many different body structures such as the pancreas, testes, brain, and muscles used for movement (skeletal muscles).
    