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Congenital disorder of glycosylation type Ib (CDG-Ib) is an inherited metabolic disorder that impairs the production of glycoproteins, which are proteins that have attached carbohydrates. In type Ib, there is a defect in an enzyme called phosphomannose isomerase.
If left untreated, the disease can cause a wide array of problems including chronic diarrhea, a failure to grow at the expected rate, a loss of protein from the body, vomiting, low blood sugar, difficulty in forming blood clots, and liver disease.
CDG-Ib can be effectively treated by taking supplements of mannose, a sugar. With this supplement, life can be relatively normal. Without it, symptoms of the disease can be life-threatening. For this reason, early diagnosis and treatment is important.
CDG-Ib is distinct from other forms of CDG in that it does not affect the central nervous system. People with CDG-Ib are intellectually normal.
CDG-Ib is extremely rare, although the exact frequency is unknown.
CDG-Ib is treated with oral supplements of mannose, a sugar. People with CDG-Ib who begin mannose treatment show improvement in most of the symptoms of the disease. Treatment with mannose must be lifelong.
With early and regular treatment, a person with CDG-Ib can live a near-normal life. Without it, the disease can be fatal. Generally, the prognosis will vary depending on the severity of symptoms and their response to mannose treatment.
A catalog of human genes and genetic disorders authored by staff at Johns Hopkins University and elsewhere and published by the National Institutes of Health's National Center for Biotechnology Information. Please note that this information is written in highly technical language.