What you carry at this position in your DNA and what research says about it.
Lung Cancer Risk: 10/10 evidence, 15 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): C/C
Typical Lung Cancer and Nicotine Dependence Risk
Two copies of the C allele are associated with typical lung cancer risk and lower susceptibility to nicotine dependence. This genotype is also linked to better baseline lung function.
What this genotype means: Typical baseline risk of lung cancer; Lower susceptibility to nicotine dependence; Better baseline lung function.
Sample genotype (not yours): C/G
Moderately Higher Lung Cancer and Nicotine Dependence Risk
One copy of the G allele is linked to a moderately increased risk of lung cancer and nicotine dependence. It also slightly reduces lung function compared to the typical genotype.
What this genotype means: Moderately higher risk of lung cancer; Slightly increased nicotine dependence; Slightly reduced lung function.
Sample genotype (not yours): G/G
Higher Lung Cancer and Nicotine Dependence Risk
Two copies of the G allele are associated with a significantly higher risk of developing lung cancer and increased nicotine dependence. This genetic profile is also linked to lower baseline lung function and a higher likelihood of chronic respiratory diseases.
What this genotype means: Significantly higher risk of lung cancer; Increased susceptibility to nicotine dependence; Reduced baseline lung function.
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 [1]. These receptors are widely expressed in both the central nervous system and peripheral tissues, including the lungs [2]. They play a critical role in mediating the cellular responses to acetylcholine and exogenous nicotine [1]. Genetic variations in this gene have been heavily implicated in smoking behaviors, nicotine addiction, and respiratory diseases [3].
Variant Impact: Located in the 5 prime untranslated region (UTR) of the CHRNA5 gene, rs55781567 is a regulatory variant. This regulatory region is crucial for controlling the translation efficiency and overall expression levels of the receptor subunit [4]. The C to G nucleotide change at this position alters the expression profile of CHRNA5 in lung tissues [2]. Specifically, the G allele is associated with lower mRNA expression levels of the functional subunit [2]. This expression imbalance is thought to alter nicotinic receptor signaling, contributing to increased susceptibility to lung diseases and nicotine addiction [1].
Key Insight: The G allele of this variant not only increases the risk of lung cancer but also makes it significantly harder to quit smoking by increasing nicotine dependence.
Location: CHRNA5. Chromosome 15 · 15q25.1 · 78.6 Mb
Estimated prevalence by population
Global 49.0%; European 42.2%; African 53.0%; East Asian 93.3%; South Asian 59.8%; Americas 56.3%; Ashkenazi 41.2%; Finnish 45.3%; Middle Eastern 34.3%; Amish 34.0%.
Estimated CC genotype frequency.
Global 41.3%; European 45.5%; African 39.6%; East Asian 6.6%; South Asian 35.1%; Americas 37.5%; Ashkenazi 46.0%; Finnish 44.0%; Middle Eastern 48.5%; Amish 48.6%.
Estimated CG genotype frequency.
Global 9.6%; European 12.3%; African 7.4%; East Asian 0.1%; South Asian 5.1%; Americas 6.2%; Ashkenazi 12.8%; Finnish 10.7%; Middle Eastern 17.2%; Amish 17.4%.
Estimated GG genotype frequency.
Showing effects for C/C genotype
Cancer & Oncology
Lung Cancer
Lung Cancer. Evidence: 10/10. Source: PMID 27393504. Typical Risk.
Neurology & Mental Health
Addiction & Reward
Nicotine Dependence. Evidence: 5/10. Source: PMID 29196725. Typical.
Organ Systems
Respiratory Health
Lung Function. Evidence: 10/10. Source: PMID 26634245. Typical.
Chronic Lung Disease. Evidence: 10/10. Source: PMID 39024449. Typical Risk.
Showing effects for C/G genotype
Lung Cancer. Evidence: 10/10. Source: PMID 27393504. ~1.26x Higher Risk.
Nicotine Dependence. Evidence: 5/10. Source: PMID 29196725. Increased Risk.
Lung Function. Evidence: 10/10. Source: PMID 26634245. Slightly Reduced.
Chronic Lung Disease. Evidence: 10/10. Source: PMID 39024449. Increased Risk.
Showing effects for G/G genotype
Lung Cancer. Evidence: 10/10. Source: PMID 27393504. ~1.5x Higher Risk.
Lung Function. Evidence: 10/10. Source: PMID 26634245. Reduced.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Two C alleles are associated with a typical, baseline risk of developing lung cancer [1]. Susceptibility to nicotine dependence is generally lower compared to G allele carriers [2]. Better baseline lung function, characterized by higher FEV1/FVC ratios, is also common with this genotype [3]. Furthermore, a lower risk of chronic lung diseases and other respiratory conditions is observed [4]. The C allele is linked to higher expression of the functional CHRNA5 subunit in lung tissues, which supports normal nicotinic receptor signaling [5]. While this genotype is protective relative to G carriers, maintaining a smoke-free lifestyle remains essential for overall lung health.
Typical baseline risk of lung cancer; Lower susceptibility to nicotine dependence; Better baseline lung function.
Sample genotype: CG (Heterozygous)
A single copy of the G allele is associated with a moderate increase in the risk of lung cancer [1]. Nicotine dependence is also moderately higher, which can influence smoking habits and the difficulty of smoking cessation [2]. Lung function measurements, such as the FEV1/FVC ratio, tend to be slightly lower compared to the typical C/C genotype [3]. The presence of one G allele is also linked to a slightly elevated risk of chronic respiratory diseases [4]. These effects are mediated by altered nicotinic receptor subunit expression in the respiratory tract [5]. Minimizing exposure to cigarette smoke and other environmental pollutants is highly beneficial for maintaining respiratory health.
Moderately higher risk of lung cancer; Slightly increased nicotine dependence; Slightly reduced lung function.
Sample genotype: GG (Homozygous)
Inheriting two copies of the G allele significantly increases the risk of developing lung cancer, with studies showing an odds ratio of approximately 1.26 or higher [1]. Nicotine dependence is also strongly elevated, making smoking cessation more challenging [2]. Research indicates that the G allele is linked to lower baseline lung function, as measured by the FEV1/FVC ratio [3]. Susceptibility to chronic lung diseases and other respiratory conditions is also higher with this genotype [4]. The biological mechanism involves altered expression of the CHRNA5 gene in lung tissues, which affects nicotinic receptor function [5]. Avoiding tobacco smoke exposure is the most critical preventive measure for maintaining respiratory health.
Significantly higher risk of lung cancer; Increased susceptibility to nicotine dependence; Reduced baseline lung function.
Variants with shared genetic architecture
rs17486278 · CHRNA5 Gene · Chr 15 · Lung Disease Risk
rs16969968 · CHRNA5 Gene · Chr 15 · Nicotine Dependence Risk
rs2036527 · CHRNA5 Gene · Chr 15 · Smoking and Lung Cancer Risk
In vitro and ex vivo analysis of CHRNA3 and CHRNA5 haplotype expression.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com