Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to hereditary hemorrhagic telangiectasia ?
    ### Response:
    Mutations in the ACVRL1, ENG, and SMAD4 genes cause hereditary hemorrhagic telangiectasia.  Hereditary hemorrhagic telangiectasia type 1 is caused by mutations in the gene ENG. Type 2 is caused by mutations in the gene ACVRL1. Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome is caused by mutations in the gene SMAD4.
    