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. 2016 Dec;104(6):1665-1670.
doi: 10.3945/ajcn.116.139030. Epub 2016 Oct 12.

Transcobalamin 776C→G Polymorphism Is Associated With Peripheral Neuropathy in Elderly Individuals With High Folate Intake

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Free PMC article

Transcobalamin 776C→G Polymorphism Is Associated With Peripheral Neuropathy in Elderly Individuals With High Folate Intake

Hathairat Sawaengsri et al. Am J Clin Nutr. .
Free PMC article

Abstract

Background: The 776C→G polymorphism of the vitamin B-12 transport protein transcobalamin gene (TCN2) (rs1801198; Pro259Arg) is associated with a lower holotranscobalamin concentration in plasma. This effect may reduce the availability of vitamin B-12 to tissues even when vitamin B-12 intake is adequate. Clinical outcomes associated with vitamin B-12 insufficiency could potentially be worsened by high folate intake.

Objective: We determined the association of the TCN2 776C→G polymorphism and folate intake with peripheral neuropathy in elders with normal plasma concentrations of vitamin B-12.

Design: Participants in this cross-sectional study (n = 171) were from a cohort of community-based, home-bound elderly individuals aged ≥60 y who underwent an evaluation by physicians including an assessment for peripheral neuropathy. Participants were administered food-frequency and general health status questionnaires, anthropometric measurements were taken, and a fasting blood sample from each subject was collected.

Results: Odds of neuropathy were 3-fold higher for GG genotypes than for CC genotypes (OR: 3.33; 95% CI: 1.15, 9.64). When folate intake was >2 times the Recommended Dietary Allowance (800 μg), GG genotypes had 6.9-fold higher odds of neuropathy than CC genotypes (OR: 6.9; 95% CI: 1.31, 36.36). There was no difference between the genotypes in the odds of peripheral neuropathy when folate intake was ≤800 μg (OR: 1.5; 95% CI: 0.18, 12.33).

Conclusion: The TCN2 776C→G polymorphism is associated with increased odds of peripheral neuropathy in the elderly, even with a normal vitamin B-12 status, especially if their folate intake is >2 times the Recommended Dietary Allowance.

Keywords: TCN2 776C>G polymorphism; folate; folic acid; peripheral neuropathy; transcobalamin; vitamin B-12.

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