Transcobalamin II 775G>C polymorphism and indices of vitamin B12 status in healthy older adults

Joshua W. Miller, Marisa I. Ramos, Marjorie G. Garrod, Margaret A. Flynn, Ralph Green

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


A common polymorphism (775G>C) in the vitamin B12 transport protein, transcobalamin II (TClI), has been identified in which proline replaces arginine at codon 259. We determined the influence of TCII genotype on indices of B12 status, including total serum B12, the amount of B12 bound to TCII (holoTCII), methylmalonic acid, and homocysteine, in 128 healthy older adults (ages 40-88 years). Mean total B12 and homocysteine concentrations were not significantly different among the 3 genotypes. Mean holoTCII concentration was significantly higher in those subjects homozygous for the proline form of TCII (PP) compared with those homozygous for the arginine form (RR) and heterozygotes (PR) (P ≤ .006). In addition, mean methylmalonic acid concentrations were significantly lower in the PP and PR groups compared with the RR group (P ≤ .02). The PP genotype may be more efficient in delivering B12 to tissues, resulting in enhanced B12 functional status. TCII genotype may thus influence susceptibility to B12 deficiency.

Original languageEnglish (US)
Pages (from-to)718-720
Number of pages3
Issue number2
StatePublished - Jul 15 2002

ASJC Scopus subject areas

  • Hematology


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