Why does severe B12 deficiency primarily impair erythropoiesis (red blood cell production) in bone marrow, rather than equally affecting all rapidly dividing cells?

💡 Explanation

B12 deficiency specifically hinders erythropoiesis because the synthesis of DNA precursors like thymidine requires B12 as a crucial cofactor for enzymes involved in nucleotide metabolism. Therefore, red blood cell production is uniquely sensitive, rather than other cell types, due to high proliferation rates and stringent DNA requirements.

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