Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Fragile X syndrome ?
    ### Response:
    What causes fragile X syndrome? Mutations (changes) in the FMR1 gene cause fragile X syndrome (FXS). This gene carries instructions to make a protein called the fragile X mental retardation 1 protein. The FMR1 gene contains a section of DNA called a CGG triplet repeat, which normally repeats from 5 to around 40 times.
    