National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Congenital disorders of glycosylation

Congenital disorders of glycosylation (CDG) are a group of inherited metabolic disorders that affect a process called glycosylation. Glycosylation is the complex process by which all human cells build long sugar chains that are attached to proteins, which are called glycoproteins. There are many steps involved in this process, and each step is triggered by a type of protein called an enzyme. Individuals with a CDG are missing one of the enzymes that is required for glycosylation. The type of CDG that a person has depends on which enzyme is missing. Currently, there are 19 identified types of CDG.[1] CDG type IA is the most common form. The symptoms of CDG vary widely among affected individuals. Some people have severe developmental delay, failure to thrive, and multiple organ problems, while others have diarrhea, low blood sugar (hypoglycemia), liver problems, and normal developmental potential.[2]
Last updated: 9/21/2011

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 25 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormal circulating carbohydrate concentration 0011013
Abnormal subcutaneous fat tissue distribution
Abnormal fat tissue distribution below the skin
0007552
Abnormality of coagulation 0001928
Abnormality of immune system physiology 0010978
Abnormality of retinal pigmentation 0007703
Aplasia/Hypoplasia of the cerebellum
Absent/small cerebellum
Absent/underdeveloped cerebellum
[ more ] 		0007360
Aplasia/Hypoplasia of the nipples
Absent/small nipples
Absent/underdeveloped nipples
[ more ] 		0006709
Cerebral cortical atrophy
Decrease in size of the outer layer of the brain due to loss of brain cells
0002120
Elevated hepatic transaminase
High liver enzymes
0002910
Failure to thrive
Faltering weight
Weight faltering
[ more ] 		0001508
Global developmental delay 0001263
Strabismus
Cross-eyed
Squint
Squint eyes
[ more ] 		0000486
Wide intermamillary distance
Wide-spaced nipples
Widely spaced nipples
Widely-spaced nipples
[ more ] 		0006610
30%-79% of people have these symptoms
Abnormal pericardium morphology 0001697
Abnormality of vision
Abnormality of sight
Vision issue
[ more ] 		0000504
Broad forehead
Increased width of the forehead
Wide forehead
[ more ] 		0000337
Cardiomyopathy
Disease of the heart muscle
0001638
Hypergonadotropic hypogonadism 0000815
Hypoglycemia
Low blood sugar
0001943
Seizure 0001250
5%-29% of people have these symptoms
Abnormal intestine morphology
Abnormality of the intestine
0002242
Ascites
Accumulation of fluid in the abdomen
0001541
Decreased liver function
Liver dysfunction
0001410
Nephropathy 0000112
Peripheral neuropathy 0009830
Showing of 25 |
Last updated: 7/1/2020
Because CDG type Ix can be caused by different enzyme deficiencies (and the deficiency in this type is typically not known), the symptoms and prognosis cannot be predicted. The various types of CDG often have different symptoms and a different prognosis. Even individuals with the same type of CDG may not have the same symptoms and prognosis.
Last updated: 9/23/2013

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

  • RareConnect has an online community for patients and families with this condition so they can connect with others and share their experiences living with a rare disease. The project is a joint collaboration between EURORDIS (European Rare Disease Organisation) and NORD (National Organization for Rare Disorders).

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Congenital disorders of glycosylation. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • What are the symptoms and prognosis for individuals with CDG Ix?  We are pending tests results from an institute in Belgium to obtain a more specific diagnosis for my 13-month-old son. He has had a liver transplant at 6 months due to liver failure, coagulopathy, ascites, protein losing enteropathy (?), failure to thrive, and hypoglycemia. CT and MRI do not show any brain abnormalities.  He does not yet crawl or stand on his own, possibly because he was hospitalized for four months. I am worried about his developmental delay. He does have minimal delay in speech. See answer


  1. About CDG. The CDG Family Network. August 2010; http://www.cdgs.com/_about.html. Accessed 9/21/2011.
  2. Sparks E, Krasnewich DM. Congenital Disorders of Glycosylation Overview. GeneReviews . August 2011; http://www.ncbi.nlm.nih.gov/books/NBK1332/. Accessed 9/21/2011.