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Danon disease is a rare genetic condition characterized by weakening of the heart muscle (cardiomyopathy), weakening of the muscles used for movement (skeletal muscles myopathy), and intellectual disability. This condition is a type of lysosomal storage disorder. Lysosomes are compartments within the cell that use enzymes to break down large molecules into smaller ones that the cell can use. In Danon disease there is a defect in the wall (membrane) of the lysosome. The defect is caused by variations (mutations) in the _LAMP2 _gene. Danon disease is inherited in an X-linked dominant pattern. In this type of inheritance, males tend to be more severely affected than females and develop symptoms at a younger age. Treatment is aimed at addressing the symptoms present in each individual and may require a team of specialists.
Source: GARD Last updated on 05-01-20
The symptoms of Danon disease vary from case to case and depend on gender. In general, the condition is characterized by cardiomyopathy, weakening of the skeletal muscles, and intellectual disability. Males usually develop the signs and symptoms of the condition earlier than females and are more severely affected. In males, the symptoms typically present in childhood or adolescence, while females may not have symptoms until early adulthood.
Cardiomyopathy is the most common symptom of Danon disease and occurs in all males with the condition. Most (90%) affected men have hypertrophic cardiomyopathy, which causes the heart muscle to become thicker and more rigid than normal. A smaller number (10%) have dilated cardiomyopathy, which weakens and enlarges the heart. Both of these conditions affect the heart's ability to efficiently pump blood through the body and can cause serious complications, including heart failure and premature death. Many women with Danon disease also develop cardiomyopathy. Of these women, about half develop hypertrophic cardiomyopathy and the other half develop dilated cardiomyopathy.
People with Danon disease may also have other heart-related signs and symptoms, including a fluttering or pounding in the chest (palpitations), an abnormal heartbeat (arrhythmia), or chest pain. Many affected individuals also have abnormalities of the electrical signals that control the heartbeat (conduction abnormalities). The most common conduction abnormality seen in individuals with Danon disease is Wolff-Parkinson-White syndrome.
Most men and about half of women with Danon disease also have skeletal myopathy. The muscles most often affected are those in the back, upper arms, shoulders, neck, and thighs. Many men also have elevated levels of an enzyme called creatine kinase (CPK) in their blood, which is an indicator of muscle disease.
Most men with Danon disease also have mild intellectual disability. In contrast, women tend to have normal intellectual development. Less common signs and symptoms may also be present, including gastrointestinal disease, breathing problems, and vision abnormalities.
Last updated on 05-01-20
Danon disease is caused by a variant (mutation) in the LAMP2 _gene. _LAMP2 stands for “lysosomal-associated membrane protein 2.” Danon disease may also be caused by loss of genetic material (deletion) of the region of the chromosome X where the LAMP2 gene is located (Xq24).
Last updated on 05-01-20
Treatment is aimed at addressing the symptoms present in each individual. This may require a team of specialists in addition to the primary care physician, including a cardiologist, neurologist, ophthalmologist, geneticist, genetic counselor, rehabilitation physician, educational specialist, and physical therapist. Because Danon disease can be associated with rapidly progressive cardiomyopathy and sudden death, careful monitoring of heart disease is required. Medications for heart disease may be a first line of treatment. Aggressive interventions may be recommended for people showing signs of progressive heart failure (e.g., early intervention with heart transplantation or implantable cardioverter-defibrillator). Assessment of muscle strength should be performed regularly. Physical therapy may help maintain muscle strength and flexibility. Males with intellectual disabilities should receive appropriate educational interventions.
Last updated on 05-01-20
Yang Z, McMahon CJ, Smith LR, Bersola J, Adesina AM, Breinholt JP, Kearney DL, Dreyer WJ, Denfield SW, Price JF, Grenier M, Kertesz NJ, Clunie SK, Fernbach SD, Southern JF, Berger S, Towbin JA, Bowles KR, Bowles NE. Danon disease as an underrecognized cause of hypertrophic cardiomyopathy in children. Circulation. 2005 Sep 13;112(11):1612-7. Epub 2005 Sep 6.
Last updated on 04-27-20
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