Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to Andersen-Tawil syndrome ?
    ### Response:
    Mutations in the KCNJ2 gene cause Andersen-Tawil syndrome.  The KCNJ2 gene provides instructions for making a protein that forms a channel across cell membranes. This channel transports positively charged atoms (ions) of potassium into muscle cells. The movement of potassium ions through these channels is critical for maintaining the normal functions of muscles used for movement (skeletal muscles) and cardiac muscle.
    