Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to familial thoracic aortic aneurysm and dissection ?
    ### Response:
    Mutations in any of several genes are associated with familial TAAD. Mutations in the ACTA2 gene have been identified in 14 to 20 percent of people with this disorder, and TGFBR2 gene mutations have been found in 2.5 percent of affected individuals. Mutations in several other genes account for smaller percentages of cases.
    