Specialty endocrinology OMIM 300257 | ICD-10 E74.0 MeSH D052120 | |
Danon disease (or glycogen storage disease Type IIb) is a metabolic disorder.
Contents
Danon disease is an X-linked lysosomal and glycogen storage disorder associated with hypertrophic cardiomyopathy, skeletal muscle weakness, and intellectual disability.
Genetics
It is associated with LAMP2. The status of this condition as a GSD has been disputed.
History
Danon disease was characterized by Moris Danon in 1981. Dr. Danon first described the disease in 2 boys with heart and skeletal muscle disease (muscle weakness), and intellectual disability.
The first case of Danon disease reported in the Middle East was a family diagnosed in the eastern region of United Arab Emirates with a new LAMP2 mutation; discovered by the Egyptian cardiologist Dr. Mahmoud Ramadan the associate professor of Cardiology in Mansoura University (Egypt) after doing genetic analysis for all the family members in Bergamo, Italy where 6 males were diagnosed as Danon disease patients and 5 female were diagnosed as carriers; as published in Al-Bayan newspaper in 20 February 2016 making this family the largest one with patients and carriers of Danon disease.
Danon Disease has overlapping symptoms with another rare genetic condition called 'Pompe' disease. Microscopically, muscles from Danon Disease patients appear similar to muscles from Pompe disease patients. However, intellectual disability is rarely, if ever, a symptom of Pompe disease. Negative enzymatic or molecular genetic testing for Pompe disease can help rule out this disorder as a differential diagnosis.
Symptoms
Males
In males the symptoms of Danon Disease are more severe. Features of Danon Disease in males are:
Females
In females the symptoms of Danon Disease are less severe. Common symptoms of Danon Disease in females are:
Causes of Danon Disease
Although the genetic cause of Danon Disease is known, the mechanism of disease is not well-understood. Danon disease involves a genetic defect (mutation) in a gene called LAMP2, which results in a change to the normal protein structure. While the function of the LAMP2 gene is not well understood, it is known that LAMP2 protein is primarily located in small structures within cells called lysosomes.