Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to Troyer syndrome ?
    ### Response:
    Troyer syndrome is caused by a mutation in the SPG20 gene. The SPG20 gene provides instructions for producing a protein called spartin, whose function is not entirely understood. Researchers believe that spartin may be involved in a variety of cell functions, from breaking down proteins to transporting materials from the cell surface into the cell (endocytosis).
    