Progression of Danon disease with medical imaging: two case reports.

Danon disease is a rare X-linked dominant genetic disorder caused by loss-of-function mutations in the lysosome-associated membrane protein 2 gene. Progression of Danon disease is unknown because of its rare incidence in a diverse ethnic population. We report longitudinal data from two patients who were diagnosed with Danon disease by a genetic test. The evaluation protocol included electrocardiographic monitoring, echocardiography, and magnetic resonance imaging. Progression of hypertrophic cardiomyopathy to dilated cardiomyopathy was observed in the first patient. He died from sudden cardiac arrest. The second patient is currently suffering from hypertrophic cardiomyopathy. Development of the hypertrophic phase progressing into the dilated phase in Danon disease may provide useful information for early identification and clinical decisions in patients with this disease.