Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to Poland syndrome ?
    ### Response:
    The cause of Poland syndrome is unknown. Researchers have suggested that it may result from a disruption of blood flow during development before birth. This disruption is thought to occur at about the sixth week of embryonic development and affect blood vessels that will become the subclavian and vertebral arteries on each side of the body.
    