G
Genetic Archaeology
GENETIC ARCHAEOLOGY // PROFILE

GC

Vitamin D Binding Protein

CHR 4
4q13.3

Overview

The GC gene encodes the Vitamin D-binding protein (DBP), also known as group-specific component. It is the main transport protein for Vitamin D in the blood and significantly influences how much Vitamin D is biologically available.

📍 Chromosomal Position

4q13.3 (Chromosome 4)

🧬 Gene Category

Vitamins

🔬 Inheritance

Complex

📊 Prevalence

C allele ~20-30%

Function & Significance

GC (DBP) has several vital functions in the body:

  • Transport: Binds Vitamin D metabolites (such as 25-OH-D) and delivers them to target cells.
  • Storage: Acts as a reservoir for Vitamin D in the circulation.
  • Immune Function: DBP is involved in macrophage activation and plays a role in the immune response.
  • Bioavailability: It regulates the ratio between bound (inactive) and free (active) Vitamin D.

🚛 The Taxi for Vitamin D

Think of the GC protein as a taxi. It collects Vitamin D produced by the body or ingested through food and transports it to where it is needed (e.g., bones or the immune system). If there are too few taxis or they work less efficiently, the measurable Vitamin D level in the blood drops significantly.

🧬 Relevant SNPs

The variant rs2282679 is one of the strongest genetic predictors of Vitamin D levels:

rs2282679
4:71753443
Allele 1

A

/

Allele 2

C

Significance: rs2282679 (A>C) – Influence on the concentration of the binding protein.

• AA (Wild type): Normal concentration of the binding protein.

• CC / AC: Associated with lower concentrations of binding protein and thus lower total values of 25-hydroxyvitamin D [25(OH)D].

⚠️ Risk for Vitamin D Deficiency

Individuals with the CC genotype have a statistically significantly increased risk of chronically low Vitamin D levels. This can affect bone density and increase the risk of respiratory infections if not counteracted.

☀️ Synergy with VDR

While the GC gene determines how much Vitamin D is transported, the VDR gene determines how well the body responds to it. A combination of unfavorable variants in both genes makes monitoring blood levels particularly important.

📚 Data Sources

  • OMIM: #139200 – Online Mendelian Inheritance in Man
  • dbSNP: rs2282679 – SNP Database (NCBI)
  • Lancet Diabetes & Endocrinology: Genetic determinants of Vitamin D status
  • Nature Genetics: Genome-wide association study of Vitamin D

Last Update: February 2026

Biological Function

The GC gene encodes a protein that binds Vitamin D metabolites and transports them to various tissues. It plays a crucial role in maintaining Vitamin D homeostasis and influences the bioavailability of free Vitamin D in the bloodstream.

Associated Conditions

Vitamin D Deficiency Osteoporosis Autoimmune Diseases Respiratory Diseases
Molecular Analysis

Analyzed Markers

rs2282679 Risk Factor
Pos: 4:71753443 | Alleles: A/C

C-allele: Associated with significantly lower levels of Vitamin D Binding Protein and often lower total 25-Hydroxyvitamin D levels in blood.