MTM1 and cataract: The autosomal-dominant form of myotubular myopathy [50,61-63,76] also has to be differentiated from myotonic dystrophy and other autosomal-dominant disorders with numerous central nuclei on muscle biopsy, particularly in cases where mutations in the currently known CNM genes have been excluded, as clinical findings such as cataracts or electrical myotonia (i.e. myotonic bursts on needle EMG) [155,156] suggest that some of the families reported in the premolecular era were affected by myotonic dystrophy rather than autosomal-dominant centronuclear myopathy.