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Research and Facts
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CDG syndrome

Codes

ICD-10: E77.8

ORPHA: 137

General information

Estimated occurrence
2-3 per 100,000 live births. PMM2-CDG is the most common CDG syndrome.
Cause

CDG syndromes are caused by mutations (changes) in genes resulting in a disturbed capacity of the cells to produce or break down glycoproteins, so called “complex sugars”. This process in the body is important, among other things, for giving proteins the right shape and for transporting them through the cell. Most CDG syndromes have an autosomal and recessive inheritance. CDG syndromes are a heterogeneous group and there are about 130 known variants. They are usually referred to by the name of the gene-CDG, for example PMM2-CDG (previously called CDG type 1a), which is the most common type.

General symptoms

CDG syndromes are metabolic disorders that affect all parts of the body, but particularly cause dysfunctions in the central and peripheral nervous system. Common symptoms include varying degrees of intellectual disability, delayed gross motor skill development, low muscle tone (hypotonia), impaired balance, impaired movement coordination, muscle weakness (primarily in the legs), strabismus and other visual impairments such as reduced night vision. About 50% of individuals with CDG syndromes have epilepsy. During infancy, common problems include feeding difficulties, diarrhoea, constipation and poor weight gain. Several different organs may also be affected, for example the heart (cardiomyopathy or fluid in the pericardium), the liver (liver fibrosis), the thyroid gland (hypothyroidism) and the skeleton (osteoporosis, scoliosis, kyphosis).

There are CDG types with immunodeficiency and thus an increased sensitivity to infections. Absent puberty is common in girls. CDG syndromes may also cause a coagulation disorder with an increased risk of either haemorrhage or thrombosis. Stroke-like episodes are also common, these are usually transitory but may in some cases result in residual conditions. The medical complications usually stabilize during adolescence. The ability to speak is in most cases very limited, while language comprehension is usually better. Spinal and thoracic deformities develop eventually. Most people become dependent on a wheelchair or a rollator/walking frame.

There is no treatment that cures PMM2-CDG. There are various symptom-reducing medicines. For some CDG types, supplying missing sugar molecules or a ketogenic diet may have a good symptom-reducing effect.

Synonyms

Congenital glycosylation syndromes, congenital disorder of glycosylation, previously called carbohydrate deficient glycoprotein.

Orofacial/odontological symptoms

Eating difficulties and frequent vomiting are common, particularly during infancy. Impaired oral-motor function and low muscle tone may cause speech difficulties, impaired saliva control and bite abnormalities. Many people with CDG syndromes habitually bite or suck on objects and gnash their teeth during the day. Dental wear and erosion is common. Individuals with a CDG type that causes immunodeficiency (AIG12-CDG) are more sensitive to infections and more often contract gingival infections, cold sores and aphthous stomatitis. An increased risk of enamel changes, dental caries and gingivitis has been described for a certain CDG type (COG6-CDG). In case of osteoporosis, medication with bisphosphonate may occur, which the dentist should be informed of.

Advice on follow-up and treatment

  • People with CDG syndromes should make early contact with a dentist for strengthened preventive care and oral health information. Many have difficulties with participating in their dental care situation. It is very important that habituation to dental care begins early with frequent and continuous contact.
  • It is recommended to contact a doctor before invasive dental treatment in case of medication with bisphosphonate preparations or anticoagulants, and in case of other medical risk conditions, such as heart defects.
  • In case of CDG with coagulation disorder or medication with anticoagulants, special dental care is required in connection with procedures that cause haemorrhage, such as dental extraction, extensive tartar removal and surgery. It is important to check the PT (INR) level before treatment. Consult a specialist dentist.
  • If dental erosion, intense bruxism and/or biting behaviour occurs, it is important to give information and provide objects suitable for biting, and to consider installing a protective mouthguard to limit dental wear.
  • Tooth, eruption, and occlusal development should be monitored. In case of malocclusion, an orthodontist should be contacted at an early stage for planning correction and treatment.
  • Oral-motor training and stimulation may be considered in case of eating difficulties, speech difficulties and impaired saliva control.
  • Speech, language, and communication impairments should be investigated by a speech pathologist, as well as the need for augmentative and alternative communication (AAC).

Sources

National Board of Health and Welfare Ågrenska
Updated: 2023-01-05 13:16