Carriers of Duchenne muscular dystrophy (DMD) often have no severe symptoms of the scelet muscles, but they may develop a poor heart function due to the involvement of the heart muscle. Ultrasound of the heart is recommended, but it can detect a cardiac affection only after the heart has already become weaker. Cardiac magnetic resonance tomography can detect myocardial fibrosis already at preserved heart function and may facilitate early therapy. In our study, diagnosed carriers of DMD will undergo examinations of the heart by blood tests, EKG, heart ultrasound and magnetic resonance at enrollment and after one year in order to assess the extent of cardiac affection and its association with the clinical development.