Intrinsic factor deficiency

Other Names: IFD; Pernicious anemia, congenital, due to defect of intrinsic factor; Congenital pernicious anemia due to defect of intrinsic factor; Intrinsic factor, congenital deficiency of; Congenital intrinsic factor deficiency

Intrinsic factor deficiency is a rare condition that is characterized by pernicious anemia and neurological abnormalities.

Intrinsic factor is a protein that helps your intestines absorb vitamin B12. It is made by cells in the stomach lining.Intrinsic factor binds to vitamin B12. After attaching, intrinsic factor and B12 travel to the intestines to be absorbed into the bloodstream. Vitamin B12 is needed for red blood cells to form and grow.

Some people do not make enough intrinsic factor or have a condition that destroys it. If your body does not make enough intrinsic factor, you can develop a type of vitamin B12 deficiency called pernicious anemia.

Surgical removal of the stomach and certain other health conditions can also cause you to stop making intrinsic factor.

Cause

Intrinsic factor deficiency is caused by changes (mutations) in the GIF gene.

Inheritance

Autosomal recessive inheritance, a 25% chance

It is inherited in an autosomal recessive manner.

Signs and symptoms

If your body does not make enough intrinsic factor, you can develop a type of vitamin B12 deficiency called pernicious anemia. Most affected people develop signs and symptoms of the condition before age 5 years which may include failure to thrive and symptoms related to anemia (i.e. fatigue, pale skin, etc). Without early diagnosis and treatment, nervous system damage may occur which can be associated with confusion; depression; and numbness or tingling in the hands and/or feet.

Diagnosis

Tests for intrinsic factor insufficiency:

• Anti-intrinsic factor antibody (Specific to pernicious anemia).
• Anti-parietal cells antibody.
• Schilling test: less commonly used, if the antibodies are negative, it is preformed to assist Cbl uptake. Done by injecting free Cbl intr-muscularly and oral intake of radiolabeled Cbl, if the intrinsic factor is sufficient and no issue in its function, then the urine will show the radiolabeled Cbl, otherwise will not.

Treatment

In most countries, intramuscular injections of vitamin B12 are used to treat pernicious anemia.Orally administered vitamin B12 is absorbed without intrinsic factor, but at levels of less than one percent than if intrinsic factor is present. Despite the low amounts absorbed, oral vitamin B12 therapy is effective at reducing symptoms of pernicious anemia.Vitamin B12 can also be given sublingually, but there is no evidence that this route of administration is superior to the oral route. Despite evidence of efficacy of oral vitamin B12 treatment, only Canada and Sweden routinely prescribe this route of administration.

NIH genetic and rare disease info

• NIH info on Intrinsic factor deficiency

Intrinsic factor deficiency is a rare disease.

Intrinsic factor deficiency Resources
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