Question: What is (are) Danon disease ?
Answer: Danon disease is a condition characterized by weakening of the heart muscle (cardiomyopathy); weakening of the muscles used for movement, called skeletal muscles, (myopathy); and intellectual disability. Males with Danon disease usually develop the condition earlier than females and are more severely affected. Signs and symptoms begin in childhood or adolescence in most affected males and in early adulthood in most affected females. Affected males, on average, live to age 19, while affected females live to an average age of 34. Cardiomyopathy is the most common symptom of Danon disease and occurs in all males with the condition. Most affected men have hypertrophic cardiomyopathy, which is a thickening of the heart muscle that may make it harder for the heart to pump blood. Other affected males have dilated cardiomyopathy, which is a condition that weakens and enlarges the heart, preventing it from pumping blood efficiently. Some affected men with hypertrophic cardiomyopathy later develop dilated cardiomyopathy. Either type of cardiomyopathy can lead to heart failure and premature death. Most women with Danon disease also develop cardiomyopathy; of the women who have this feature, about half have hypertrophic cardiomyopathy, and the other half have dilated cardiomyopathy. Affected individuals can have other heart-related signs and symptoms, including a sensation of fluttering or pounding in the chest (palpitations), an abnormal heartbeat (arrhythmia), or chest pain. Many affected individuals have abnormalities of the electrical signals that control the heartbeat (conduction abnormalities). People with Danon disease are often affected by a specific conduction abnormality known as cardiac preexcitation. The type of cardiac preexcitation most often seen in people with Danon disease is called the Wolff-Parkinson-White syndrome pattern. Skeletal myopathy occurs in most men with Danon disease and about half of affected women. The weakness typically occurs in the muscles of the upper arms, shoulders, neck, and upper thighs. Many males with Danon disease have elevated levels of an enzyme called creatine kinase in their blood, which often indicates muscle disease. Most men with Danon disease, but only a small percentage of affected women, have intellectual disability. If present, the disability is usually mild. There can be other signs and symptoms of the condition in addition to the three characteristic features. Several affected individuals have had gastrointestinal disease, breathing problems, or visual abnormalities.
Source: GHR