Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by myotonic dystrophy ?
    ### Response:
    Myotonic dystrophy affects at least 1 in 8,000 people worldwide. The prevalence of the two types of myotonic dystrophy varies among different geographic and ethnic populations. In most populations, type 1 appears to be more common than type 2. However, recent studies suggest that type 2 may be as common as type 1 among people in Germany and Finland.
    