Congenital Disorders of Glycosylation
National Organization for Rare Disorders, Inc.
- CDG syndrome
- carbohydrate-deficient glycoprotein syndromes
Congenital disorders of glycosylation (CDG) is an umbrella term for an expanding group of rare metabolic disorders that share similar but not identical genetic changes (mutations) and biochemical activity. These disorders involve a normal, but complex, chemical process known as glycosylation. Glycosylation is the process by which sugar chains (glycans) are created, altered and chemically attached to certain proteins or fats (lipids). When these sugar molecules are attached to proteins, they form glycoproteins; when they are attached to lipids, they form glycolipids. Glycoproteins and glycolipids have varied important functions within the body and are essential for the normal growth and function of numerous tissues and organs. Glycosylation involves many different genes, which encode many different proteins such as enzymes. A deficiency or lack of one of these enzymes can lead to a variety of symptoms potentially affecting multiple organ systems. CDG can affect virtually any part of the body, although most cases usually have an important neurological component. CDG can be associated with a broad variety of symptoms and can vary in severity from mild cases to severe, disabling or life-threatening cases. CDG are usually apparent in infancy. Individual CDG are caused by a mutation to a specific gene. Most CDG are inherited as autosomal recessive conditions.
CDG were first reported in the medical literature in 1980 by Dr. Jaak Jaeken, et al. More than 50 different forms of CDG have been identified in the ensuing years. Several different names have been used to describe these disorders including carbohydrate-deficient glycoprotein syndromes. Recently, researchers have proposed a classification system that names each subtype by the official abbreviation of its defective gene followed by a dash and CDG. For example, congenital disorder of glycosylation type 1a is now known as PMM2-CDG. PMM2 is the defective gene that causes this subtype of CDG. CDG are a rapidly growing disease family and information about these disorders is constantly changing.
CLIMB (Children Living with Inherited Metabolic Diseases)
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CDG Family Network
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Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
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Last Updated: 1/9/2012
Copyright 2012 National Organization for Rare Disorders, Inc.