What you carry at this position in your DNA and what research says about it.
Lung Disease Risk: 10/10 evidence, 15 publications.
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Sample genotype (not yours): A/A
Typical Lung Disease Risk and Better Lung Function
Two copies of the common A allele are associated with typical baseline risks for lung cancer and COPD. This profile is also linked to better overall lung function and lower daily cigarette consumption.
What this genotype means: Typical baseline risk of lung cancer; Better overall lung function metrics; Lower likelihood of heavy nicotine dependence.
Sample genotype (not yours): A/C
Increased Risk of Lung Disease and Heavier Smoking
One copy of the C allele is associated with an increased risk of lung cancer, COPD, and cardiovascular issues. This profile is also linked to a tendency to smoke more cigarettes per day.
What this genotype means: Elevated risk of lung cancer and COPD; Reduced lung function measurements; Increased tendency for higher daily cigarette consumption.
Sample genotype (not yours): C/C
Highest Risk of Lung Disease and Heavier Smoking
Two copies of the C allele are associated with the highest risk of lung cancer, COPD, and cardiovascular conditions. This profile is also strongly linked to heavier smoking habits and reduced lung function.
What this genotype means: Highest risk of lung cancer and COPD; Significantly reduced lung function metrics; Strongest genetic predisposition to heavy smoking.
Gene function and biological role
Gene Function: The CHRNA5 gene encodes the alpha-5 subunit of the nicotinic acetylcholine receptor, which is a ligand-gated ion channel. These receptors are widely expressed in both the central nervous system and peripheral tissues, including the lungs. They play a crucial role in mediating the effects of nicotine and regulating neurotransmitter release. Genetic variations in this gene cluster are heavily implicated in nicotine dependence and smoking behaviors [1]. Furthermore, altered receptor function or expression levels are directly linked to respiratory diseases and lung malignancies [2].
Variant Impact: An intronic single nucleotide polymorphism, rs17486278 is located within the CHRNA5 gene. As an intron variant, it is believed to influence gene expression or splicing rather than directly altering the amino acid sequence of the receptor. This genetic change has been identified as a significant contributor to lung cancer susceptibility across diverse populations, including those of African and European ancestry [2]. It is also strongly associated with chronic obstructive pulmonary disease and altered lung function measurements [3].
Key Insight: This genetic variant influences both the behavioral drive to smoke and the physical susceptibility of lung tissue to disease, creating a dual-layered risk profile.
Location: CHRNA5. Chromosome 15 · 15q25.1 · 78.6 Mb
Estimated prevalence by population
Global 46.8%; European 42.5%; African 49.9%; East Asian 52.4%; South Asian 58.1%; Americas 56.2%; Ashkenazi 37.9%; Finnish 45.2%; Middle Eastern 33.4%; Amish 34.9%.
Estimated AA genotype frequency.
Global 43.0%; European 45.4%; African 41.5%; East Asian 40.0%; South Asian 36.2%; Americas 37.5%; Ashkenazi 47.3%; Finnish 44.0%; Middle Eastern 48.8%; Amish 48.3%.
Estimated AC genotype frequency.
Global 10.2%; European 12.1%; African 8.6%; East Asian 7.6%; South Asian 5.6%; Americas 6.3%; Ashkenazi 14.8%; Finnish 10.7%; Middle Eastern 17.8%; Amish 16.7%.
Estimated CC genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Lung Cancer
Lung Cancer. Evidence: 10/10. Source: PMID 39024449. Typical Risk.
Organ Systems
Respiratory Health
COPD. Evidence: 9/10. Source: PMID 28166215. Typical Risk.
Lung Function. Evidence: 10/10. Source: PMID 26634245. Better Function.
Neurology & Mental Health
Addiction & Reward
Smoking Intensity. Evidence: 8/10. Source: PMID 36477530. Typical.
Cardiovascular & Metabolic
Heart Disease
Cardiovascular Risk. Evidence: 8/10. Source: PMID 37845353. Typical Risk.
Showing effects for A/C genotype
Lung Cancer. Evidence: 10/10. Source: PMID 39024449. Increased Risk.
COPD. Evidence: 9/10. Source: PMID 28166215. ~1.4x Increased Risk.
Lung Function. Evidence: 10/10. Source: PMID 26634245. Reduced Function.
Smoking Intensity. Evidence: 8/10. Source: PMID 36477530. Increased.
Cardiovascular Risk. Evidence: 8/10. Source: PMID 37845353. Increased Risk.
Showing effects for C/C genotype
Lung Cancer. Evidence: 10/10. Source: PMID 39024449. Highest Risk.
COPD. Evidence: 9/10. Source: PMID 28166215. Highest Risk.
Lung Function. Evidence: 10/10. Source: PMID 26634245. Lowest Function.
Smoking Intensity. Evidence: 8/10. Source: PMID 36477530. Highest.
Cardiovascular Risk. Evidence: 8/10. Source: PMID 37845353. Highest Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Inheriting two copies of the A allele represents the typical genetic baseline for this variant. Large-scale genetic studies, including the Million Veteran Program, show that this genotype is associated with a lower risk of developing lung cancer compared to carriers of the C allele [1]. It is also linked to a reduced risk of chronic obstructive pulmonary disease (COPD) and chronic bronchitis [1]. Spirometric measurements indicate that individuals with this genotype tend to have a higher FEV1/FVC ratio and forced expiratory volume, reflecting better overall lung function [2]. Additionally, this genotype is associated with a lower likelihood of heavy smoking and fewer cigarettes smoked per day [3]. There is also a lower risk of developing cardiovascular complications such as atherosclerosis and abdominal aortic aneurysms [1]. This genetic profile is particularly common, representing the major allele configuration globally. Understanding this baseline can help contextualize personal health and lifestyle choices.
Typical baseline risk of lung cancer; Better overall lung function metrics; Lower likelihood of heavy nicotine dependence.
Sample genotype: AC (Heterozygous)
Possessing one copy of the C allele is associated with an elevated susceptibility to several respiratory and cardiovascular conditions. Research indicates that this genotype increases the risk of developing lung cancer [1]. It is also significantly linked to a higher incidence of chronic obstructive pulmonary disease (COPD), with an odds ratio of approximately 1.42 for risk allele carriers [2]. Individuals with this genotype often exhibit reduced lung function, characterized by lower forced expiratory volume and decreased lung diffusing capacity [3]. Furthermore, this genetic variation is associated with heavier smoking behaviors, including a higher number of cigarettes smoked per day [4]. The risk also extends to cardiovascular diseases, showing associations with atherosclerosis and abdominal aortic aneurysms [1]. Having a single copy of the risk allele means these elevated risks are intermediate compared to non-carriers and double-copy carriers. This highlights the importance of minimizing environmental risk factors like smoking.
Elevated risk of lung cancer and COPD; Reduced lung function measurements; Increased tendency for higher daily cigarette consumption.
Sample genotype: CC (Homozygous)
Double copies of the C allele represent the highest genetic risk profile at this locus for respiratory and cardiovascular diseases. Multi-ancestry genome-wide association studies have consistently linked this genotype to an increased risk of lung cancer [1]. The risk of chronic obstructive pulmonary disease (COPD) is also significantly elevated, accompanied by a higher likelihood of chronic bronchitis and emphysema [2]. Spirometric assessments show that individuals with this genotype have lower forced expiratory volume and reduced lung diffusing capacity, indicating compromised lung function [3]. This genotype is also strongly associated with increased nicotine dependence and a higher number of cigarettes smoked daily [4]. Beyond respiratory health, there is an elevated risk of cardiovascular issues, including atherosclerosis, peripheral vascular disease, and abdominal aortic aneurysms [2]. This combination of risks makes avoiding tobacco exposure particularly critical for individuals with this genetic profile. It underscores how genetic factors can influence both behavioral tendencies and physical disease susceptibility.
Highest risk of lung cancer and COPD; Significantly reduced lung function metrics; Strongest genetic predisposition to heavy smoking.
Variants with shared genetic architecture
rs55781567 · CHRNA5 Gene · Chr 15 · Lung Cancer Risk
rs16969968 · CHRNA5 Gene · Chr 15 · Nicotine Dependence Risk
rs2036527 · CHRNA5 Gene · Chr 15 · Smoking and Lung Cancer Risk
Genetic diversity fuels gene discovery for tobacco and alcohol use.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Content updated August 2026.
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