Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Friedreich ataxia ?
    ### Response:
    What causes Friedreich ataxia? Friedreich ataxia is caused by mutations in the FXN gene. This gene provides instructions for making a protein called frataxin. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (one guanine and two adenines) that appear multiple times in a row.
    