Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to Tourette syndrome ?
    ### Response:
    A variety of genetic and environmental factors likely play a role in causing Tourette syndrome. Most of these factors are unknown, and researchers are studying risk factors before and after birth that may contribute to this complex disorder. Scientists believe that tics may result from changes in brain chemicals (neurotransmitters) that are responsible for producing and controlling voluntary movements.
    