Danon Disease

By: Leah Garside and Nina Chandler

Danon disease is a uncommon genetic disease that causes muscle weakness (muscular dystrophy), heart disease (cardiomyopathy), and mental retardation (or learning problems).

Cellular Problem

  • The organelles affected are the vacuoles.
  • The normal job of vacuoles in animal cells is to store water, food, and waste. They also move these substances around to desired locations. Vacuoles have the additional function of assisting in the digestive and waste management process for the cell.
  • The vacuoles malfunctions happens when mutations in the LAMP2 gene leads to the production of little to no LAMP-2 protein. The role of the LAMP-2 protein is unclear to scientists. Some believe that it helps transport materials or digestive enzymes to the lysosomes. This may damage the process that vacuoles complete to transfer cellular material to lysosomes.
  • The malfunction of the vacuoles affects organisms with Danon disease because the accumulation of autophagic vacuoles in a human's muscle can lead to a breakdown of muscle cells. This accumulation happens when the process of combining lysosomes and autophagic vacuoles slows down.
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Disease Information

Symptoms of Danon disease:

  • Hypertrophic Cardiomyopathy- A thickening of the heart muscle, which then makes it harder for the heart to pump blood.
  • Dilated cardiomyopathy- A condition that prevents the heart from efficiently pumping blood because it has been weakened and enlarged.
  • Palpitations- a sensation of pounding in the chest.
  • Arrhythmia- An abnormal heartbeat.
  • Muscular Dystrophy- Muscle weakness.
  • Learning/mental disabilities- A mental disability may form for men, and sometimes women.The correct diagnosis of this disease is not usually identified until cardiac symptoms are present.
  • Chest pain.
  • Breathing problems.
  • Gastrointestinal disease.

Patients with Danon disease, and doctors examining patients with Danon disease will notice breathing problems and heart palpitations. Doctors will notice these conditions when listening to the patients hearts. Patients will feel these conditions as well as many other symptoms of this disease such as chest pain.

Tests done to Determine Danon Disease:

A 24-hour ECG (electrocardiogram) test is taken, as well as an ultrasound and a MRI examination. These are all tests carried out by doctors to figure out if you have Danon disease or not. In a lot of cases irregularities in the electrical impulses of the heart and cardiac rhythms are found by doctors.

Treatment Options:

There is no cure for this disease yet, but there are a number of ways to reduce the symptoms.

  • On a light note people with this disease should stay away from coffee and other caffeinated beverages, for it can aggravate cardiac arrhythmia. Arrhythmia is a condition when the heart beats with an irregular rhythm.
  • Physical exercise is also extremely important. It should be frequent, but not overly difficult and tiring.
  • At an early age some (mostly men) may consider a heart transplant, although this has not been proven to be completely successful yet.
  • If you have a case with heart failure, medication can be given.
  • Boys who experience learning disabilities may require habilitation. Habilitation is a serious step that involves a series of assessments, treatments, and assistance, along with a choice of aids, and possible counseling.
  • Some types of arrhythmia can be treated using a procedure where a catheter (thin tube) is threaded through the patient's blood vessels to treat parts of the heart. It does this by freezing or using radio waves to reach those parts of the heart where the abnormal impulses originate.

How Serious is Danon Disease?

Danon disease is uncommon, but very serious. There is no real cure for it, so most that get diagnosed with it will die at an earlier age. It has a high mortality rate.

This disease affects males much more severely than woman.

It affects the heart and the brain. These are the two very important organs in your body that you would not be able to function without.

Effect on Daily Living:

This disease has a strong effect on daily life. Patients with this disease have to spend months in the hospital and constantly have to live with a disability. The common symptom of learning disabilities gives patients a tough time learning new things. This disease is also mentally hard and can take a long time to recover from.

Age and Inheritability:

  • The Danon disease is X-linked dominant, which means that the gene is located in the X chromosome. Men will always inherit this gene since they only have one X chromosome, and a person only needs to inherit one copy of an affected X chromosome to develop the Danon symptoms.
  • Woman have two X chromosomes, but only one gets affected. Therefore they develop serious symptoms of this disease later in life.
  • A woman carrying this gene only has a fifty percent chance of passing it to their offspring, while men carrying this affected gene will pass it down to their daughters. Their sons never develop this disease because they only inherit a Y chromosome from their father.
  • The typical time of diagnosis for males is childhood through adolescence, and for females is early adulthood.
  • Affected males, on average, live to be 19, while affected females, on average, live to be 34.
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Danon Disease