Home Muscular dystrophy: Myotonic dystrophy type I

Muscular dystrophy: Myotonic dystrophy type I


Defining Characteristics

Maternal anticipation, asymmetric distal weaknes w/ myotonia, pt can make a fist but can’t open it back up easily; frontal balding, cataracts, cardiac conduction probs, endocrine dysfunction (hypogonadism, insulinR), GI hypomotility

Disease Development

Autosomal dominant inheritance associated with trinucleotide CTG repeats in myotonin-protein kinase gene on C19

Potential Causes

Maternal anticipation (increases number of CTG rpts)


5-20/100,000 live births


Clinical exam


Multisystem disorder; possible complete heart block