Effect of vitamin B12-deficiency on % 5 mdC¹ and [3 H]methyl-acceptance capacity² for DNA extracted from coagulated blood clots³ and uncoagulated EDTA-blood cell pellets⁴.

1Methyldeoxycytidine as a percentage of total deoxycytidine in DNA digests, measured by LC-MS/MS (see Methods). 2Capacity of DNA to incorporate [3 H] from [3 H-methyl]SAM (cpm incorporated per 250 ng DNA) in the presence of Sssi DNA methyltransferase (see Methods). 3Post-centrifugation, blood clots were retained after serum was removed from plain blood tubes. 4Post-centrifugation, blood pellets were retained after plasma was removed from EDTA blood tubes. 5Subjects with plasma vitamin B12>148 pmol/L. 6Subjects with plasma vitamin B12<148 pmol/L. Power analysis: >80% power to detect a *4%, **10%, or ***15% difference in means [62].