Pernicious Anemia

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WHO-ICD-10 version:2010

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

Nutritional anaemias

OMIM Number

170900

Mode of Inheritance

Autosomal dominant ?

Description

Pernicious anemia (PA) is a form of anemia caused by a functional deficiency of vitamin B-12, also known as cobalamin. Proper intestinal absorption of B-12 requires the presence of an intrinsic factor. Congenital pernicious anemia is a rare condition where PA sets in even in the presence of adequate consumption of B-12, due to a significantly decreased level of the intrinsic factor. Congenital PA is indicated by an early onset and the presence of similarly affected siblings. The acquired form, on the other hand, has its onset later in life. Atrophic gastritis and certain autoimmune conditions are known to precipitate acquired PA. The signs and symptoms of PA begin very slowly and may go unnoticed for a long time before diagnosis. These features include diarrhea or constipation, fatigue, loss of appetite, pale skin, lack of concentration, shortness of breath, and bleeding gums. In severe cases, nervous system damage may result in confusion, depression, and numbness in fingers and toes. The condition is most common in people of North European ancestry, while it is rarer in people of Asian or African origin.

Tests used to confirm a suspected diagnosis of the condition include blood tests, Schilling's test to check for vitamin B-12 absorption, and occasionally, bone marrow biopsy. Treatment involves administering vitamin B-12, orally or by way of injections. This treatment needs to be continued lifelong, since PA is currently incurable. Prognosis is excellent if treatment is started early. However, permanent nerve damage can ensue if treatment is not started within six-months of appearance of the nervous symptoms.

Epidemiological evidence, including familial clustering of the condition points to pernicious anemia as having a significant heritable component. This observation is supported by the fact that PA tends to co-occur with other autoimmune diseases. In congenital PA, autoantibodies directed against the Intrinsic Factor lead to a deficiency of the protein, resulting in malabsorption of B12. Genetic factors may play a role in the pathogenesis of adult-onset forms of the condition too. While the absolute cause is unknown, there are two major hypotheses; firstly PA is a defect in immunological tolerance to a particular antigen found in the stomach, thyroid gland, pancreas, and skin; and second it is a defect in a metabolic pathway that is common to these tissues. The disease has also been found in patients that have deletions in chromosome 18. These are associated with selective IgA deficiencies.

Epidemiology in the Arab World

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Other Reports

Jordan

Abdella et al. (1990) described a 62-year old Jordanian lady who presented with pernicious anemia, atrophic gastritis, vitiligo, premature graying of hair, and primary infertility. Several members of her family were affected with various autoimmune disorders.

[Abdella N, Mouro M, Al Soussi A. Pernicious anemia associated with endocrinopathies and family clustering of various autoimmune disorders. Kuwait Med J. 1990; 24(2):182-3.]

Sudan

Abu-Sin and Ahmed (1978) reported three Sudanese patients with pernicious anaemia. Laboratory tests including routine blood counts, bone marrow aspiration, serum Vitamin B12 and folate evaluation, the Schilling test, gastric acid secretion estimates, and other tests confirmed the diagnosis of pernicious anaemia in all three cases. Following diagnosis, the patients were given Vitamin B12 injection therapy and they all responded favorably.

Yemen

Al-Ghazaly et al. (2006) reported on their experience in the pattern of hematological diseases diagnosed by bone marrow examination in a referral hematology center in Yemen. Between November 1999 and November 2005, 785 patients >14 years old were evaluated by bone marrow examination. Among these patients, three had pernicious anemia.

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