Glycosylation

 Congenital Disorders of Glycosylation

 Congenital Disorders of Glycosylation (CDG; previously known as carbohydrate-deficient glycoprotein syndrome) are diseases affecting brain and other organs. 

Cause 

In CDG, the primary biochemical defects occur in the N-glycosylation pathway which takes place in the cytoplasm, endoplasmic reticulum, and in cellular organelles phosphomannomutase-2 (a mannose-processing enzyme) results in CDG type I (the most common form). Other enzymatic defects have been identified, but the biochemical bases of some CDG sub-types are still to be determined. involved in protein and lipid synthesis. Defective 

Symptoms

In infants, CDG type Ia develops low muscle tone, severe delay in their development, and abnormalities in the brain.

Children with CDG type Ia have inverted nipples and unusual distribution of fat (mainly in suprapubic and buttock region). Hypoglycaemia, seizures, stroke-like episodes, damaged retina, impaired heart contractility, vomiting, liver disease, diarrhoea, and a bleeding tendency are some other symptoms.

 Treatment 

Any effective treatment is not available for CDG; however, CDG type Ib (occurring due to deficiency of phosphomannose isomerase enzyme) can be treated by oral administration of mannose.