Pernicious anemia: intrinsic factor failure and spinal cord degeneration
THE CONTEXT
The target passage continues the discussion of impaired vitamin B12 absorption in pernicious anemia and explains its irreversible spinal cord complication.
Impaired absorption
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Failure of vitamin B12 absorption is the most common cause of pernicious anemia, rather than dietary deficiency.
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The absorption defect can result from failure of intrinsic factor secretion due to autoimmune disease affecting parietal cells, or from production of anti-intrinsic factor antibodies.
Mechanism of spinal cord degeneration
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Pernicious anemia causes irreversible spinal cord degeneration through failure of methylation of one arginine residue in myelin basic protein.
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This methylation failure results from methionine deficiency in the central nervous system rather than secondary folate deficiency.