In people who are not supplementing with vitamin B12, high vitamin B12 levels may be associated with kidney and liver disease, hematological abnormalities, solid neoplasms, and hematological malignancies.
Elevated levels of vitamin B12 may also be influenced by certain genetic factors, including polymorphisms in genes related to B12 metabolism. Two noteworthy areas of genetic variation in this context are the transcobalamin II gene (TCN2) and methionine synthase reductase (MTRR), although the direct association with high B12 levels can be complex and multifactorial.
- Transcobalamin II (TCN2) Gene Polymorphisms: Transcobalamin II is a protein that binds vitamin B12 in the blood and helps in its transport to cells where it's needed. Certain polymorphisms in the TCN2 gene can affect the binding affinity of transcobalamin II for vitamin B12, potentially influencing blood levels of the vitamin.
- Methionine Synthase Reductase (MTRR) Gene Polymorphisms: The MTRR gene is important in the remethylation of homocysteine to methionine, a process that involves vitamin B12. Polymorphisms in MTRR can influence enzyme activity, potentially impacting B12 metabolism and its levels in the body.
- FUT2 (Fucosyltransferase 2) Gene: FUT2 gene variants also predispose towards elevated serum concentrations of vitamin B12.
