Vitamin C (SLC23A1)

SLC23A1 · rs33972313

SLC23A1 encodes the sodium-dependent vitamin C transporter SVCT1. Variants in this gene have been associated with differences in circulating ascorbate in research. They do not replace a measurement of vitamin C status.

Key points

rs33972313 alters the transport capacity for vitamin C in the gut.
One study reported higher average ascorbate levels with the common G allele.
A genetic association is not an individual deficiency finding.

#The markers

SLC23A1 encodes the sodium-dependent vitamin C transporter SVCT1, which takes up ascorbate in the gut. The missense variant rs33972313 was associated with circulating ascorbate; in the study by Kobylecki et al. (2015), the mean was about 11 percent higher with the common G allele. A group difference does not predict an individual's blood level. A second SNP in the same gene, rs10063949, explained additional variance in that study.

#What it means

Genetic markers can be used as instruments in population-level Mendelian randomization research. This does not make rs33972313 a personal measurement or an explanation for low vitamin C in an individual.

#Context

The genetic effect is real but moderate; diet and smoking shift the level more strongly. Genome shows the markers as technical evidence within the built-in panel 'Vitamins A-E'.

What Genome measures. The genotypes at the SLC23A1 markers rs33972313 (missense) and rs10063949.

Sources

1Kobylecki et al., 2015 Genetically high plasma vitamin C and risk of ischemic heart disease: a Mendelian randomization study. American Journal of Clinical Nutrition 101:1135-1143. doi.org/10.3945/ajcn.114.104497