Danon Disease

Danon disease is a rare genetic condition, which is characterized by cardiomyopathies, weakening of the skeletal muscles, as well the potential for intellectual disability. Symptoms include fluttering/pounding in the chest, abnormal heartbeat, or chest pain. Individuals may also have gastrointestinal symptoms, breathing problems, or other abnormalities. Other accompanying disorders include HCM or dilated cardiomyopathy. This is a lysosomal storage disorder, which affects the walls of lysosomes, which usually help break down substances. In Danon disease, there is an impairment of lysosomal function. It is caused by a mutation in the LAMP2 gene and is an X-linked pattern, which makes males more likely to develop symptoms at a younger age than females. Males develop symptoms around adolescence while females develop symptoms in early adulthood.
Unfortunately, Danon disease is often associated with poor prognosis requiring transplantation in many. Males require transplantation on average before 20, females are variable and may experience heart failure later in life and which may possibly require a transplant.
Studies show that 90% of affected men have HCM. 10% have dilated cardiomyopathy which weakens and enlarges the heart. Both of these can cause the heart to efficiently pump blood which can lead to serious complications and even death.
There is no cure yet and treatment is focused on alleviating symptoms and protecting from sudden cardiac arrest with the aid of implantable defibrillators. Treatment may include a disciplinary approach including an ophthalmologist, cardiologist, neurologist, physical therapist and more. Because Danon’s is associated with rapidly progressive and aggressive cardiomyopathy as well as sudden death, careful monitoring is required.
Figure 1: Cardiac muscle from a 14 year old male with Danon disease. (A) Cross section of a heart with hypertrophy and fibrosis. (B) Stain of cardiomyocytes and fibrosis. (C) Extensive vacuolization.

“Danon Disease.” Genetic and Rare Diseases Information Center, U.S. Department of Health and Human Services, rarediseases.info.nih.gov/diseases/9730/danon-disease.
Danon disease - Genetics Home Reference. (n.d.). Retrieved February 26, 2018, from https://ghr.nlm.nih.gov/condition/danon-disease