A case of myotonic dystrophy during the clinical course of non-alcoholic steatohepatitis *
We report the case of a 42-year-old woman diagnosed with myotonic dystrophy during the clinical course of non-alcoholic steatohepatitis (NASH). She had been diagnosed fatty liver at age 33. When she was 40 years old, histopathological findings of a liver biopsy specimen indicated NASH. After that, she complained of gait disturbance. Brain CT and MRI revealed skull thickening, calcification of falx cerebri and atrophy of the lateral pterygoid muscles. She had a hatchet face. Her muscle strength was normal; she did not have grip myotonia nor percussion myotonia. On laboratory data, total cholesterol was 254 mg/dl, γGTP was 118 U/l, CK was 148 U/l, fasting plasma glucose was 103 mg/dl, fasting plasma insulin was 15.6 μU/ml, homeostasis model assessment-insulin resistance (HOMA-IR) was 3.967. A dive-bomber sound was heard on needle EMG. DM protein kinase gene analysis showed increase of CTG repeat. Occurrence of myotonic dystrophy during the clinical course of NASH is rare. NASH/non-alcoholic fatty liver disease (NAFLD) is strongly associated with insulin resistance. Insulin resistance in patients with myotonic dystrophy is highly prevalent and is due to a splicing abnormality of the insulin receptor in muscle tissue. In our patient, HOMA-IR was elevated and suggested an increase of insulin resistance. Thus, the risk of developing myotonic dystrophy should be considered in patients with NASH/NAFLD. (Accepted on February 12, 2013)
