Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Myotonic dystrophy type 1 ?
    ### Response:
    Myotonic dystrophy type 1, one of the two types of myotonic dystrophy, is an inherited type of muscular dystrophy that affects the muscles and other body systems (e.g., heart, eyes, pancreas).  Myotonic dystrophy type 1 has been categorized into three somewhat overlapping subtypes: mild, classic, and congenital (present at birth).
    