Intrinsic factor, congenital deficiency of

Congenital Intrinsic Factor Deficiency is a rare genetic disorder characterized by the body's inability to produce adequate amounts of intrinsic factor (IF), a protein essential for the absorption of vitamin B12 (cobalamin) in the intestine. This condition leads to vitamin B12 deficiency, which can result in megaloblastic anemia and neurological disorders if not diagnosed and treated early.

Causes

Congenital Intrinsic Factor Deficiency, also known as congenital pernicious anemia, is caused by mutations in the GIF gene, which is responsible for the production of intrinsic factor. This condition is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected.

Symptoms

The symptoms of Congenital Intrinsic Factor Deficiency can vary but often include signs of vitamin B12 deficiency such as fatigue, weakness, pale skin, red tongue, gastrointestinal disturbances, and neurological problems like numbness and tingling in the hands and feet. In severe cases, untreated vitamin B12 deficiency can lead to serious neurological damage.

Diagnosis

Diagnosis of Congenital Intrinsic Factor Deficiency involves a combination of clinical evaluation, laboratory tests, and genetic testing. Blood tests may show megaloblastic anemia and low levels of vitamin B12. The Schilling test, once a common diagnostic tool, has been largely replaced by more specific tests for antibodies against intrinsic factor and parietal cells, although these are not typically elevated in congenital cases. Genetic testing can confirm a diagnosis by identifying mutations in the GIF gene.

Treatment

Treatment for Congenital Intrinsic Factor Deficiency focuses on managing vitamin B12 deficiency and involves lifelong vitamin B12 supplementation. This can be administered through high-dose oral supplements or intramuscular injections of vitamin B12. Early diagnosis and treatment are crucial to prevent the development of complications.

Prognosis

With early diagnosis and appropriate treatment, individuals with Congenital Intrinsic Factor Deficiency can lead normal, healthy lives. However, they will require lifelong supplementation of vitamin B12 to prevent complications associated with its deficiency.

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