An unusual case with myotonia

We report an unusual case involving a patient with myotonia. A 57-year-old man had multisystemic symptoms including skeletal muscle weakness, atrophy and percussion myotonia, cataract, heart involved, gastrointestinal tract symptoms, and urinary incontinence. The electromyography revealed myotonic discharges. Muscle biopsy showed myopathic features and a striking number of ring fibers. It was genetically proven that the case was not myotonic dystrophy type 1 (DM1) or 2 (DM2). The case might be DM3 or an unusual case of unclassified myopathy with multisystemic damage.