OBJECTIVETo carry out clinical and genetic analysis for three pedigrees affected with myotonic dystrophy type 1 (DM1).

METHODSThree probands with clinically diagnosed DM and their familial members were recruited. Clinical data of the patients including clinical manifestations, electrocardiogram (ECG), and electromyogram (EEG) was collected.

RESULTSThe clinical symptoms of all probands have progressed slowly and included myotonia, muscle weakness and muscle atrophy as the main manifestations. Disorders of other systems have included cataract, arrhythmia, alopecia, sexual dysfunction, and cognitive impairment. The EEG of the probands showed characteristic myotonia discharges. Genetic analysis revealed over 50 CTG repeats at the 3' end of the DMPK gene in all three probands.

CONCLUSIONDM1 is a complex hereditary disorder involving multiple systems and overlaps with other diseases. In addition to clinical symptoms and EEG, genetic testing can facilitate its diagnosis at early stages.