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. 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.

Individuals with a CDG can have developmental delays. Depending on the individual, manifestations can range from normal development to severe developmental delay. Parents may begin to recognize a delay in development in their child around 4 months of age. Many children require early intervention therapy, including occupational, physical, and speech therapy.

Yes. You can view organizations providing information and supportive resources on our Web site by clicking on the Organizations tab on this page, or by clicking on the following link: http://rarediseases.info.nih.gov/gard/10307/congenital-disorders-of- glycosylation/resources/5

Protein-losing enteropathy is the abnormal loss of protein from the digestive tract, or the inability of the digestive tract to take in proteins.

If a person has CDG type Ix it means that the enzyme deficiency that causes the disorder is unknown. Some people are diagnosed with type Ix if they have not had genetic testing to determine a more specific subtype. Other individuals are diagnosed with type Ix because testing has not provided a specific diagnosis.

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.