Definition of Danon disease

Danon disease: A genetic disorder characterized by heart problems, mental retardation and muscle weakness. Changes in the retina of the eye, leading to visual disturbances, may be present. Males are more severely affected and show symptoms in childhood or early adolescence, while affected females usually develop the symptoms later, in adolescence or adulthood.

The disease is due to a mutation in the gene for LAMP-2 (which stands for lysosome-associated membrane protein 2.), a glycoprotein molecule (a molecule made up of carbohydrate + protein) that is normally located on the membrane surrounding the lysosome (a packet of powerful corrosive enzymes that degrade "garbage" within cells).

The gene for LAMP-2 is on the X chromosome and is inherited in a pattern known as X-linked dominant. A person with one copy of the defective X chromosome will develop the disease, in contrast to an X-linked recessive condition, in which two copies of the defective X chromosome are necessary for the condition to develop. This means that mothers with Danon Disease will typically pass on the risk of disease to approximately half of their sons and daughters, while affected fathers will pass the defective gene to all of their daughters but none of their sons..

The heart disease component can be very severe and potentially fatal. Heart transplantation is the only curative treatment at this moment for the fatal cardiac component of Danon disease.

Danon disease is named for Dr. M.J. Danon who (together with colleagues) originally described it 1981 as "lysosomal glycogen storage disease with normal acid maltase."

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