Danon Disease

What is Danon Disease?

Danon disease is also called Antopol disease, glycogen storage cardiomyopathy, glycogen storage disease IIB, GSD IIB, pseudoglycogenesis II, lysosomal glycogen storage disease without acid maltase deficiency and vacuolar cardiomyopathy and myopathy, X-linked.

No matter what it is called, this condition is a fatal genetic disease that kills boys at the average age of 19 and women at the average age of 34. It causes a weakening of the muscles (including the heart) and intellectual disability.

There is unfortunately no cure for Danon disease. It is caused by a mutation in a gene called LAMP2. Just what specific mutation is involved is currently unknown since there are more than 70 mutations recorded of LAMP2.Babies with Danon disease are born looking and acting like normal babies. The disease hits all races and economic classes.

What are the Symptoms of Danon Disease?

Symptoms can vary from patient to patient. In general, boys have different symptoms than girls. Death for both men and women is usually from heart failure.

Symptoms include

Boys usually first suffer incoordination and muscle weakness, visual problems and learning difficulties. Eventually the disease progresses to weakened heart muscle, shortness of breath and feeling exhausted all of the time. Other problems can include lung problems, gastrointestinal disease, liver problems and enlargement of the spleen.

Girls often do not show any symptoms until they become adults. The fist symptom is usually heart disease, followed by visual problems. A minority of women patients have muscle problems, learning disabilities, breathing difficulties or gastrointestinal disease.

Danon Disease Causes

The exact cause of this disease is as yet unknown. However, it is known that Danon disease is a genetic defect and that the gene involved is called LAMP2. The defect is carried along the X chromosome, making it more prevalent in boys than girls. When a patient has this disease, there is a mutation or damage to this gene. When it’s been damaged, it will no longer make the protein it’s supposed to make. The function of this gene is not yet understood, but we know that the protein made by LAMP2 is found in the lysosome structures of the cells. The structures help the cells to rid themselves of waste products, and the lack of the LAMP2 gene disrupts the function of the lysosomes.

How is Danon Disease Treated?

As mentioned, there is no cure for Danon disease. Death will be from heart failure, even if there has been a successful heart transplant. Before death treatment can help the patient make the most of the time he or she has left. Men have lived as long as 30 after a heart transplant and some women reach 50.

Treatment includes

Focuses on treating the symptoms. For example, physical therapy, braces and canes can help coordination problems. Medicines for any kind of heart disease is also given to Danon disease patients. Patients may need antidepressants or therapy to deal with the emotional aftermath of their diagnosis.

As with any other heart conditions, patients should avoid caffeine.

Danon Disease Prevention

Because there is no known exact cause of this disease, there is little that can be done to prevent it. The prevention techniques that are used are meant to prevent the worst effects of this disease. Primarily, they seek to prevent the heart failure and heart attacks that often result from this disease. Women and young men with Danon disease are often recommended a heart transplant to avoid the early heart attacks and other health problems associated with it. Getting a heart transplant allows the patient to live longer and to avoid any cardiovascular problems.

Some parents opt to test their unborn children for the disease. This allows mothers to prevent their child from having this disease by making reproductive choices. There are no known lifestyle choices that make this disease more likely. There are few known causes of this disease, and if you suspect this condition has been inherited, a healthcare team will be able to provide advice on how to limit its impact on your body and teach you about what you need to do when you experience a heart attack. Many preventative measures can lessen the symptoms and the risk of serious heart episodes.

Resources
Last Reviewed:
October 09, 2016
Last Updated:
December 12, 2017