GC (vitamin D binding protein)

rs2282679 · rs4588 · rs7041

The GC gene encodes vitamin D binding protein (DBP), which transports most of the circulating vitamin D. Common variants change the DBP isoform and thereby the measured 25-OH-D level. GC is the strongest known genetic influence on vitamin D status.

Binding protein and isoforms

DBP binds and transports most of the vitamin D in blood. The variants rs4588 and rs7041 define the three common isoforms Gc1F, Gc1S and Gc2, which differ in binding affinity. rs2282679 is tightly linked to these and a reliable marker for the genetic influence on the level.

What it means

Those genetically prone to lower DBP or vitamin D levels tend to have lower readings, even with the same sun and dietary intake. This complements the blood measurement but does not replace it: the genotype explains a predisposition, the level shows the actual state. For vitamin D work this is the genetic layer behind the 25-OH-D value.

Context

GC is well documented, but the effect is moderate and only part of the total variance. Genome shows the markers as technical evidence, to be read together with measurements and lifestyle.

What Genome measures. The genotypes at rs2282679, rs4588 (Thr436Lys) and rs7041 (Asp432Glu), which influence the DBP isoform (Gc1F, Gc1S, Gc2) and the vitamin D level.

Related topics

VDR (vitamin D receptor)rsIDs, microarray and SNP lookup

Sources

  1. 1Wang et al., 2010 Common genetic determinants of vitamin D insufficiency: a genome-wide association study. The Lancet 376:180–188. doi.org/10.1016/S0140-6736(10)60588-0
  2. 2Powe et al., 2013 Vitamin D-binding protein and vitamin D status of black Americans and white Americans. New England Journal of Medicine 369:1991–2000. doi.org/10.1056/NEJMoa1306357