Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Bartter syndrome ?
    ### Response:
    Bartter syndrome is a group of very similar kidney disorders that cause an imbalance of potassium, sodium, chloride, and related molecules in the body.  In some cases, Bartter syndrome becomes apparent before birth. The disorder can cause polyhydramnios, which is an increased volume of fluid surrounding the fetus (amniotic fluid).
    