Abstract
The present study reports on a family with two members affected by Danon disease but having different phenotypes. The clinical manifestations of Danon disease include cardiomyopathy, skeletal myopathy and different degrees of intellectual disability that varies greatly among patients. The present case study reports on two siblings, an older sister and a younger brother, with Danon disease from an affected pedigree, presenting with distinctly different phenotypes. The sister was diagnosed with dilated cardiomyopathy at the age of 26 years with an unfavorable outcome, while her younger brother presented with hypertrophic cardiomyopathy in a relatively stable state. The two probands shared the same mutation, c.974delTinsAA in exon 8, in the lysosomal-associated membrane protein-2 gene. Of note, the two patients had a pre-excitation pattern in the electrocardiogram on initial presentation and later developed atrial fibrillation (AF), which markedly aggravated heart failure. To the best of our knowledge, AF has not been widely reported in patients with Danon disease. The development of AF may have a prognostic value under these circumstances.