Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Alpha-1 antitrypsin deficiency ?
    ### Response:
    What causes alpha-1 antitrypsin deficiency? Alpha-1 antitrypsin deficiency (AATD) is caused by mutations in the SERPINA1 gene. This gene gives the body instructions to make a protein called alpha-1 antitrypsin (AAT), which protects the body from an enzyme called neutrophil elastase.
    