What you carry at this position in your DNA and what research says about it.
Vitamin D Levels: 10/10 evidence, 60 publications.
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Sample genotype (not yours): A/A
Lower Vitamin D and Higher COPD Risk
Inheriting two copies of the A allele is associated with lower circulating vitamin D levels and an increased risk of respiratory issues. Ex-smokers with this profile may face a higher likelihood of developing chronic obstructive pulmonary disease.
What this genotype means: Lower circulating vitamin D levels; Increased risk of vitamin D deficiency; Higher risk of COPD in ex-smokers.
Sample genotype (not yours): A/C
Typical Vitamin D and COPD Risk
Carrying one copy of each allele typically results in intermediate vitamin D-binding protein activity and average circulating vitamin D levels. This profile is not associated with an elevated risk of respiratory conditions or vitamin deficiency.
What this genotype means: Typical circulating vitamin D levels; Average risk of vitamin D deficiency; Baseline COPD risk.
Sample genotype (not yours): C/C
Higher Vitamin D and Lower COPD Risk
Inheriting two copies of the C allele is linked to optimal circulating vitamin D levels and a lower risk of deficiency. This genetic profile also offers relative protection against chronic obstructive pulmonary disease and respiratory decline.
What this genotype means: Higher baseline vitamin D levels; Reduced risk of vitamin D deficiency; Lower risk of COPD.
Gene function and biological role
Gene Function: The GC gene encodes the vitamin D-binding protein, which is the primary carrier of vitamin D in the bloodstream [1]. This protein binds to vitamin D metabolites and transports them to various target tissues throughout the body [1]. Beyond transport, it plays a role in regulating the amount of free, active vitamin D available to cells [2]. It also participates in immune system responses and the clearance of cellular debris [2]. Variations in this gene can significantly alter how efficiently the protein binds and releases vitamin D, directly influencing overall circulating levels of the vitamin [1].
Variant Impact: The rs7041 variant is a missense mutation that alters the amino acid at position 432 of the vitamin D-binding protein from aspartic acid to glutamic acid. This structural change directly influences the protein's binding affinity for vitamin D metabolites and its concentration in circulation [1]. The alteration affects how easily vitamin D is transported and released to tissues, which can impact bone density and immune function [3]. Research shows this variant is one of the strongest genetic determinants of circulating vitamin D levels in diverse populations [1]. It also influences susceptibility to respiratory conditions and other inflammatory disorders [4].
Key Insight: This variant is one of the single most influential genetic factors determining your baseline vitamin D levels, and it also plays a surprising role in protecting or predisposing your lungs to inflammatory damage.
Location: GC. Chromosome 4 · 4q13.3 · 71.8 Mb
Estimated prevalence by population
Global 33.8%; European 19.0%; African 69.5%; East Asian 50.7%; South Asian 20.2%; Americas 23.2%; Ashkenazi 16.3%; Finnish 9.7%; Middle Eastern 16.7%; Amish 28.6%.
Estimated AA genotype frequency.
Global 42.6%; European 49.2%; African 27.8%; East Asian 41.0%; South Asian 49.5%; Americas 49.9%; Ashkenazi 48.2%; Finnish 42.9%; Middle Eastern 48.3%; Amish 49.8%.
Estimated AC genotype frequency.
Global 23.6%; European 31.9%; African 2.8%; East Asian 8.3%; South Asian 30.3%; Americas 26.9%; Ashkenazi 35.5%; Finnish 47.4%; Middle Eastern 35.0%; Amish 21.6%.
Estimated CC genotype frequency.
Showing effects for A/A genotype
Nutrition & Metabolism
Vitamin & Mineral Metabolism
Vitamin D Levels. Evidence: 10/10. Source: PMID 29325163. Lower Levels.
Vitamin D Deficiency. Evidence: 10/10. Source: PMID 34852423. Increased Risk.
Organ Systems
Respiratory Health
COPD. Evidence: 3/10. Source: PMID 19996341. ~2x Higher Risk.
Pharmacogenomics
Drug Metabolism Enzyme Activity
Deferasirox Response. Evidence: 5/10. Source: PMID 30651574. Stronger Response.
Showing effects for A/C genotype
Vitamin D Levels. Evidence: 10/10. Source: PMID 29325163. Typical Levels.
Vitamin D Deficiency. Evidence: 10/10. Source: PMID 34852423. Typical Risk.
COPD. Evidence: 3/10. Source: PMID 19996341. Typical Risk.
Deferasirox Response. Evidence: 5/10. Source: PMID 30651574. Typical Response.
Showing effects for C/C genotype
Vitamin D Levels. Evidence: 10/10. Source: PMID 29325163. Higher Levels.
Vitamin D Deficiency. Evidence: 10/10. Source: PMID 34852423. Lower Risk.
COPD. Evidence: 3/10. Source: PMID 19996341. Lower Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Circulating levels of vitamin D are often significantly lower in those with this specific genetic profile [1]. Research indicates that ex-smokers carrying this genotype have approximately a twofold higher risk of developing chronic obstructive pulmonary disease (COPD) [1]. The structural form of the binding protein encoded by this genotype has a higher affinity for vitamin D, which paradoxically reduces the amount of free, active vitamin available to tissues [2]. This deficiency can impair lung function and weaken the body's natural defenses against respiratory infections [2]. Maintaining adequate vitamin D through diet or targeted supplementation may be highly beneficial, particularly for individuals with a history of smoking [1]. Additionally, this genotype is associated with a more favorable response to the iron-chelating medication deferasirox [3].
Lower circulating vitamin D levels; Increased risk of vitamin D deficiency; Higher risk of COPD in ex-smokers.
Sample genotype: AC (Heterozygous)
Balanced levels of vitamin D-binding protein are common in individuals with this heterozygous profile [1]. The presence of one C allele helps maintain typical circulating vitamin D concentrations, reducing the risk of severe deficiency compared to the A/A genotype [1]. Respiratory health and lung function generally remain within the typical range, with no significantly elevated risk of chronic obstructive pulmonary disease [2]. The binding protein functions with moderate efficiency, ensuring a steady release of active vitamin D to target tissues [3]. While overall health risks are baseline, maintaining a balanced diet and monitoring vitamin D levels during winter months remains a practical approach to wellness [1]. Response to specific medications like deferasirox is expected to be typical [4].
Typical circulating vitamin D levels; Average risk of vitamin D deficiency; Baseline COPD risk.
Sample genotype: CC (Homozygous)
Circulating concentrations of vitamin D tend to be highest in individuals with this genetic makeup [1]. The specific protein structure encoded by this genotype allows for highly efficient transport and optimal release of active vitamin D to cells [2]. This efficient delivery supports robust immune function and helps protect lung tissue from inflammatory damage [2]. Consequently, there is a lower risk of developing chronic obstructive pulmonary disease, even among those with a history of smoking [3]. Bone mineral density and overall calcium absorption are also well-supported by these optimal vitamin levels [1]. While supplementation is rarely necessary under normal conditions, maintaining a healthy lifestyle continues to support these natural genetic advantages [4].
Higher baseline vitamin D levels; Reduced risk of vitamin D deficiency; Lower risk of COPD.
Variants with shared genetic architecture
rs2282679 · GC Gene · Chr 4 · Vitamin D Levels
rs4588 · GC Gene · Chr 4 · Vitamin D Levels
rs705117 · GC Gene · Chr 4 · Vitamin D Levels
Genome-wide association study of circulating vitamin D-binding protein.
Vitamin D-binding protein contributes to COPD by activation of alveolar macrophages.
Content updated August 2026.
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