Congenital Disorders of Glycosylation

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Congenital Disorders of Glycosylation is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • carbohydrate-deficient glycoprotein syndromes
  • CDG
  • CDG syndrome

Disorder Subdivisions

  • None

General Discussion

Congenital disorders of glycosylation (CDG) is an umbrella term for a rapidly expanding group of rare genetic, metabolic disorders due to defects in complex chemical process known as glycosylation. Glycosylation is the process by which sugar ‘trees' (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 numerous important functions in all tissues and organs. Glycosylation involves many different genes, encoding 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 any part of the body, and there is nearly always 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 from 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 and colleagues. More than 80 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, Jaeken and colleagues 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.

Supporting Organizations

CDG Care

P.O. Box 3784
Pueblo, Colorado 81005
Tel: (866) 295-7910

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building
176 Nantwich Road
Crewe, CW2 6BG
United Kingdom
Tel: 4408452412173
Fax: 4408452412174

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

The Arc

1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated:  12/15/1969
Copyright  2015 National Organization for Rare Disorders, Inc.