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Pernicious AnemiaBy Naomi Bryner
https://www.youtube.com/watch?v=6OUaYcknxLU
Vitamin B12 Sources
Functions
Autoimmune mechanism Anti-intrinsic factor Abs
Anti-parietal cell Abs
Case Study Expecting cancer
Chronic fatigue
Overview
chemistry.about.com
Vitamin B12 – Sources
Dietary sources Meat, poultry, shellfish,
eggs, diary
Use about 1 μg/day
Liver storage Lasts months-decades
Requires Intrinsic Factor Secreted by gastric
parietal cells
Vitamin B12 – Functions (Andres, et al.; Song, et al.)
Methionine synthase No de novo pathway
Coupled methylation
Methylmalonyl CoA Mutase Generates radicals
Produces Succinyl-CoA
Free folate Hematopoiesis
Nucleic acids
Autoimmune mechanism (Moretti, et al.; Antico, et al.)
Anti-intrinsic factor antibodies
Intrinsic factor blocking abs Type I
Works competitively
Fills binding sites
Intrinsic factor binding abs Type II
Binds with vitamin B12
Causes precipitation
Autoimmune mechanism (Banka, et al.; Torbenson, et al.)
Anti-parietal cell antibodies
Created during type A gastric infection
Dendritic cells present H+/P+-ATPase as Ag
Th1 CD4+ T cells attack α-
and β-subunits of
H+/P+-ATPase Proton pump (H+ out, K+ in)
Constitute most coating of parietal cells
Preexisting due to prior helicobacter pylori infection Affects >50% world pop.
Only 20% show symptoms
CD4+ recognizes H+/P+-
ATPase as H. pylori
Suspected genetic causation - FUT2 gene Makes protein that is
distantly involved in H antigen production
Case Studies
Patient expecting cancer (Tisman, et al.)
Male age 75 at high risk of prostate cancer
Active vitamin B12 (IF bound) was depleted before all vitamin B12
Lack of IF bound vitamin B12 can affect DNA synthesis Overall expectation: Increase
mutation rate
In this case: Retardation of cancer growth possibly due to poor DNA synthesis
Patient with chronic fatigue (Kadikoylu, et al.)
Female age 55 examined after several months fatigue
Detection of multiple factors led to PA diagnosis
Further testing led to the diagnosis of a type 1 gastric carcinoid tumor Not generally detected alone
Fruitless biopsy
Annual follow-up examinations
Pernicious Anemia
Malabsorption of vitamin B12 due to lack of parietal cells or intrinsic factor Intrinsic factor – blocking (competition), binding (precipitation)
Parietal cells - H+/K+-ATPase ‘confused’ for helicobacter pylori
Active vitamin B12 works with methionine synthase, methylmalonyl-CoA mutase, and folate Synthase – methylation of essential amino acid
Mutase – uses radicals to make succinyl Co-A (citric acid cycle)
Folate – aids maturation of erythrocytes, methylates nucleic acids
The exact causes of the autoimmune responses related to PA are unknown Cancers (especially stomach), age-related gastric atrophy,
genetics
Literature Cited
Andres, E., Serraj, K. 2012. Optical management of pernicious anemia. Dove Medical Press [serial online] 3: 97-103.
Antico, A., Tampoia, M., Villalta, D., Tonutti, E., Tozzoli, R., and Bizzaro, N. 2012. Clinical usefulness of the serological gastric biopsy for the diagnosis of chronic autoimmune gastritis. Clinical and Developmental Immunology [serial online] ePub.
Banka, S., Ryan, K., Thomson, W., and Newman, W.G. 2011. Pernicious anemia – Genetic insights. Autoimmunity Reviews [serial online] 10(8): 455-459.
Kadikoylu, G., Yavasoglu, I., Yukselen, V., Ozkara, E., and Bolamin, Z. 2006. Treatment of solitary gastric carcinoid tumor by endoscopic polypectomy in a patient with pernicious anemia. World Journal of Gastroenterology [serial online] 12(26): 4267-4269.
Moretti, R.,Torre, P., Antonello, R.M., Cattaruzza, T., Cazzato, G., Bava, A. 2004. Vitamin B12 and folate depletion in cognition: A review. Neurology India [serial online] 52(3): 310-318.
Song, I.C., Lee, H.J., Kim, H.J., Bae, S.B., Lee, K.T., Yang, Y.J., Park, S.Y., Cho, D.Y., Kim, N.Y., Cho, I.S., and Jo, D.Y. 2013. A multicenter retrospective analysis of the clinical features of pernicious anemia in a Korean population. Journal of Korean Medical Science [serial online] 28(2): 200-204.
Tisman, G.,Kutik, S., Rainville, C. 2009. Coexistence of pernicious anemia and prostate cancer –‘an experiment of nature’ involving vitamin B12 modulation of prostate cancer growth and metabolism: a case report. Journal of Medical Case Reports [serial online] 3: 9295.
Torbenson, M., Abraham, S.C., Boitnott, J., Yardley, J.H., and Wu, T.T. 2002. Autoimmune gastritis: Distinct histological and immunochemical findings before complete loss of oxyntic glands. Modern Pathology [serial online] 15(2): 102-109.
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