Effects of TCN2 776C>G on vitamin B, folate, and total homocysteine levels in kidney transplant patients.

Abstract

Controversy exists regarding the possible associations between a single nucleotide polymorphism of the transcobalamin II encoding gene (TCN2 776C>G) and plasma levels of vitamin B(12), folate, or total homocysteine. In a cross-sectional study of 732 kidney allograft recipients, patients were categorized by TCN2 776C>G genotype. In univariate and multivariate linear regression models that allowed the outcome variables vitamin B(12), folate, and total homocysteine plasma levels to follow a gamma distribution, we tested for possible associations of allelic variants of the TCN2 776C>G gene and these three dependent variables. The allele frequency for TCN2 776C>G was 0.46. Heterozygosity or homozygosity for TCN2 776C>G was not associated with plasma levels of vitamin B(12) (776CG, P= 0.22; 776GG, P= 0.89), folate (776CG, P= 0.91; 776GG, P= 0.84), or total homocysteine (776CG, P= 0.11; 776GG, P= 0.33) even after adjustment for several possible confounders. We conclude from this largest study on the subject thus far that there are no associations between allelic variants of TCN2 776C>G and plasma vitamin B(12), folate, or total homocysteine plasma levels in kidney transplant patients.