Danon disease: focusing on heart.

Danon disease is a rare X-linked dominant lysosomal disease due to the primary deficiency of lysosome-associated membrane protein 2 (LAMP2) gene. Cardiomyopathy, skeletal myopathy and mental retardation are the typical triad of Danon disease. More than 60 LAMP2 mutations have been reported. The molecular mechanism is defects in LAMP2 protein (due to LAMP2 mutation) which causes insidious glycogen accumulation in cardiac muscle cells and resulting in cardiac hypertrophy and electrophysiological abnormalities. However, there are significant differences between the male and female Danon disease patients with regard to clinical features and cardiac manifestations. The clinical symptoms are variable, from asymptomatic to sudden cardiac death. Wolff-Parkinson-White syndrome is more common in male than female patients. Hypertrophic cardiomyopathy is predominant in male patients, whereas the similar prevalence of hypertrophic and dilated cardiomyopathy in female patients. Male patients are diagnosed usually at teenage, whereas the diagnosis and events occurred approximately 15 years later in female than male patients. Heart transplantation is the reliable treatment once the occurrence of heart failure and should be considered as early as possible due to its rapid progression.