A screening for mutation in the X-linked Emery-Dreifuss muscular dystrophy (X-EMD) gene was performed among patients affected with severe heart rhythm defects and/or dilated cardiomyopathy. Patients were selected from the database of the Department of Cardiology of the University Hospital Brno. One patient presented a mutation in the X-EMD gene and no emerin in his skeletal muscle. The patient had a severe cardiac disease but a very mild muscle disorder that had not been diagnosed until the mutations was found. This case shows that mutations in X-EMD gene, as it was shown for autosomal-dominant EMD, can cause a predominant cardiac phenotype.