GC
| is a | gene |
| is | mentioned by |
| Full name | group-specific component (vitamin D binding protein) |
| EntrezGene | 2638 |
| PheGenI | 2638 |
| VariationViewer | 2638 |
| ClinVar | GC |
| GeneCards | GC |
| dbSNP | 2638 |
| Diseases | GC |
| SADR | 2638 |
| HugeNav | 2638 |
| wikipedia | GC |
| GC | |
| gopubmed | GC |
| EVS | GC |
| HEFalMp | GC |
| MyGene2 | GC |
| 23andMe | GC |
| UniProt | P02774 |
| Ensembl | ENSG00000145321 |
| OMIM | 139200 |
| # SNPs | 23 |
| Max Magnitude | Chromosome position | Summary | |
|---|---|---|---|
| rs10488854 | 0 | 71,758,418 | |
| rs1155563 | 0 | 71,777,771 | |
| rs1491710 | 0 | 71,743,377 | |
| rs16847015 | 0 | 71,773,107 | |
| rs16847024 | 0 | 71,784,962 | |
| rs17467825 | 0 | 71,739,800 | |
| rs222016 | 0 | 71,769,258 | |
| rs222020 | 0 | 71,770,555 | |
| rs222029 | 0 | 71,779,245 | |
| rs222035 | 0 | 71,755,957 | |
| rs222040 | 0 | 71,751,215 | |
| rs2282679 | 1.5 | 71,742,666 | Less likely to suffer from vitamin D insufficiency |
| rs2298849 | 0 | 71,783,134 | |
| rs2298850 | 0 | 71,748,550 | |
| rs3733359 | 0 | 71,784,057 | |
| rs3755967 | 0 | 71,743,681 | |
| rs4588 | 0 | 71,752,606 | Affects vitamin D levels |
| rs4752 | 0 | 71,756,849 | |
| rs7041 | 1.5 | 71,752,617 | |
| rs705117 | 0 | 71,742,398 | |
| rs705120 | 0 | 71,748,423 | |
| rs842999 | 0 | 71,745,973 | |
| rs843010 | 0 | 71,790,705 |
The GC gene located on chromosome 4 encodes human group-specific component, which is the major vitamin D-binding protein (VDBP) in plasma.
The presence of absence of two common variants in the GC gene, rs7041 and rs4588, lead to proteins with slightly different characteristics and possibly an effect on circulating vitamin D levels. The protein forms and the variant combination that leads to each are:
Note that some publications use rs2282679 as a proxy for rs4588; rs2282679(A) is typically co-inherited with rs4588(C) and vica-versa.
Since a person normally has two copies of the GC gene, this leads to six possible VDBP phenotypes (or haplotypes), each identifiable from the SNP genotypes as shown:
- 1s/1s : rs7041(G;G)
- 1s/1f : rs7041(G;T) AND rs4588(C;C), or, rs7041(G;T) AND rs2282679(A;A)
- 1s/2 : rs7041(G;T) AND rs4588(A;C), or, rs7041(G;T) AND rs2282679(A;C)
- 1f/1f : rs7041(T;T) AND rs4588(C;C), or, rs7041(T;T) AND rs2282679(A;A)
- 1f/2 : rs7041(T;T) AND rs4588(A;C), or, rs7041(T;T) AND rs2282679(A;C)
- 2/2 : rs4588(A;A) or rs2282679(C;C)
Does a person's GC (VDBP) haplotype influence the amount of vitamin D circulating in their blood, i.e. serum 25(OH)D levels? Yes, at least to some extent. One large study (11,000 people;[PMID 25993554
]) reported the following averages/haplotype, in nmol/L:
- Highest vitamin D levels: haplotypes 1s/1s, 1s/1f and 1f/1f: 55.4 +/- 16.8, 53.3 +/- 17.2, 52.2 +/- 16.8, respectively
- Intermediate vitamin D levels: haplotypes 1f/2 and 1s/2: 50.5 +/- 16.3 and 50.3 +/- 15.6, respectively
- Lowest vitamin D levels: haplotype 2/2: 46.9 +/- 15.1
However, a more medically relevant question is: Does a person's VDBP haplotype influence their risk for any diseases, most particularly those that have previously been associated in at least some studies with vitamin D levels? A 2013 review of the literature concludes that while VDBP variants may influence immune modulation, disease associations reported to date are "difficult to interpret", and furthermore, "many of the association studies were insufficiently powered and failed to account for multiple comparisons".[PMID 23427793]
