Abstract
Female carriers of mutations in the dystrophin gene (DMD-carriers) may manifest clinically in the skeletal muscle, the heart, or both. Cardiac involvement may manifest before, after, or together with the muscle manifestations. A 46y female developed slowly progressive weakness of the lower and upper limbs with left-sided predominance since age 26y. Muscle enzymes were repeatedly elevated and muscle biopsy showed absence of dystrophin. MLPA analysis revealed a deletion of exons 12-29. After starting steroids at age 39y, she developed palpitations and exertional dyspnoea. Cardiac MRI at age 41y revealed mildly reduced systolic function, a slightly enlarged left ventricle, mild hypokinesia of the entire myocardium, and focal, transmural late gadolinium enhancement (LGE) of the midventricular lateral wall. She did not tolerate beta-blockers but profited from ivabradine and lisinopril. In conclusion, muscle manifestations in DMD-carriers with deletions of exons 12-29 may start years before cardiac involvement becomes clinically apparent. Progressive worsening of systolic function in DMD-carriers is attributable to progressive myocardial fibrosis, as demonstrated by LGE. Steroids may trigger the development of cardiac disease in DMD-carriers.