What you carry at this position in your DNA and what research says about it.
Heart and Lung Health: 9/10 evidence, 27 publications.
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Sample genotype (not yours): C/C
Typical Heart and Lung Function
Presence of the common C allele is associated with normal cardiovascular health and typical lung function. This genotype lacks the rare variant linked to increased risks of heart disease or airway obstruction.
What this genotype means: Typical cardiovascular risk; Normal airway response.
Sample genotype (not yours): C/T
Increased Heart and Lung Risks
Inheriting one copy of the rare T allele is associated with a higher risk of coronary artery disease and reduced lung function. It may also lead to a blunted response to certain asthma medications.
What this genotype means: Higher risk of coronary artery disease; Reduced bronchodilator response.
Sample genotype (not yours): T/T
Significantly Higher Heart and Lung Risks
Possessing two copies of the rare T allele is linked to a significantly higher risk of high blood pressure, coronary artery disease, and reduced lung capacity. It also causes a markedly blunted response to beta-agonist medications.
What this genotype means: Elevated risk of hypertension; Severely blunted response to asthma inhalers.
Gene function and biological role
Gene Function: The ADRB2 gene encodes the beta-2 adrenergic receptor, a member of the G protein-coupled receptor superfamily [1]. This receptor is highly expressed in bronchial and vascular smooth muscle, where it mediates muscle relaxation in response to adrenaline and noradrenaline [1]. Activation of the receptor leads to bronchodilation in the lungs and vasodilation in blood vessels, making it a key regulator of airway resistance and blood pressure [1]. Because of its central role in respiratory function, ADRB2 is the primary target for beta-agonist medications used to treat asthma and chronic obstructive pulmonary disease [2].
Variant Impact: A missense mutation at rs1800888 changes the amino acid at position 164 of the ADRB2 receptor from threonine to isoleucine [1]. This specific amino acid substitution occurs within the fourth transmembrane domain of the receptor, which is critical for ligand binding and signal transduction [1]. The isoleucine variant exhibits significantly reduced binding affinity and blunted signaling capacity when stimulated by adrenaline or synthetic beta-agonists [1]. As a result, less effective smooth muscle relaxation occurs in both blood vessels and airways [3]. This functional impairment underlies the variant's association with reduced lung function, elevated blood pressure, and increased cardiovascular risk [3].
Key Insight: The rare T allele reduces the beta-2 adrenergic receptor's signaling capacity by up to 90%, making standard asthma rescue inhalers far less effective.
Location: ADRB2. Chromosome 5 · 5q32 · 148.8 Mb
Estimated prevalence by population
Global 98.2%; European 97.2%; African 99.5%; East Asian 100.0%; South Asian 99.3%; Americas 97.3%; Ashkenazi 98.7%; Finnish 99.3%; Middle Eastern 94.6%; Amish 100.0%.
Estimated CC genotype frequency.
Global 1.8%; European 2.8%; African 0.5%; East Asian 0.0%; South Asian 0.7%; Americas 2.6%; Ashkenazi 1.3%; Finnish 0.7%; Middle Eastern 5.3%; Amish 0.0%.
Estimated CT genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi < 0.1%; Finnish < 0.1%; Middle Eastern 0.1%; Amish 0.0%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Heart Disease
Coronary Artery Disease. Evidence: 3/10. Source: PMID 21883537. Typical Risk.
Hypertension
Blood Pressure. Evidence: 8/10. Source: PMID 21883537. Typical.
Organ Systems
Respiratory Health
Lung Function. Evidence: 9/10. Source: PMID 30804560. Typical.
Asthma Drug Response. Evidence: 5/10. Source: PMID 11222464. Typical Response.
Showing effects for C/T genotype
Coronary Artery Disease. Evidence: 3/10. Source: PMID 21883537. Increased Risk.
Blood Pressure. Evidence: 8/10. Source: PMID 21883537. Slightly Increased.
Lung Function. Evidence: 9/10. Source: PMID 30804560. Reduced.
Asthma Drug Response. Evidence: 5/10. Source: PMID 11222464. Poorer Response.
Showing effects for T/T genotype
Blood Pressure. Evidence: 8/10. Source: PMID 21883537. Increased.
Asthma Drug Response. Evidence: 5/10. Source: PMID 11222464. Blunted Response.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
The common C allele encodes the standard threonine amino acid at position 164 of the beta-2 adrenergic receptor [1]. This receptor plays a crucial role in relaxing smooth muscle tissue, which helps dilate blood vessels and open up airways [1]. Carrying two copies of this common allele is associated with typical blood pressure levels and normal lung function measurements, such as forced expiratory volume [2]. Clinical studies indicate that individuals with this genotype do not have the elevated risk of coronary artery disease or myocardial infarction associated with the rare T variant [3]. Additionally, they show a typical, healthy response to beta-agonist medications like terbutaline, which are commonly used to treat asthma and other respiratory conditions [1].
Typical cardiovascular risk; Normal airway response.
Sample genotype: CT (Heterozygous)
The rare T allele replaces threonine with isoleucine at position 164, which significantly blunts the receptor's signaling capacity [1]. This reduced signaling can prevent blood vessels and airways from dilating fully, leading to lifelong elevated smooth muscle tone [2]. Clinical studies have linked this variant to a higher incidence of coronary artery disease, myocardial infarction, and cardiac events [3]. In addition to cardiovascular risks, carriers often show reduced lung function measurements, such as a lower FEV1/FVC ratio [4]. Furthermore, research indicates that individuals with this genotype have a poorer response to beta-agonist bronchodilators like terbutaline, as the altered receptor does not respond as effectively to these drugs [1].
Higher risk of coronary artery disease; Reduced bronchodilator response.
Sample genotype: TT (Homozygous)
Homozygosity for the rare T allele is extremely uncommon, occurring in less than 0.1% of the population, but has profound physiological effects [1]. This genotype results in beta-2 adrenergic receptors that are severely compromised in their ability to stimulate smooth muscle relaxation [2]. Consequently, individuals with this genotype are at a much higher risk for developing hypertension, particularly women, who show significantly elevated systolic and diastolic blood pressure [1]. The risk of ischemic heart disease and coronary artery events is also substantially increased compared to non-carriers [1]. Furthermore, lung function is typically reduced, and standard rescue inhalers or beta-agonist medications like terbutaline may provide very little therapeutic benefit due to the blunted receptor activity [2].
Elevated risk of hypertension; Severely blunted response to asthma inhalers.
Variants with shared genetic architecture
rs1042713 · ADRB2 Gene · Chr 5 · Asthma Inhaler Response
rs1042714 · ADRB2 Gene · Chr 5 · Cardiovascular Health
rs1042711 · ADRB2 Gene · Chr 5 · Metabolic and Airway Health
Blunted cardiac responses to receptor activation in subjects with Thr164Ile beta(2)-adrenoceptors.
Childhood lung function and the association with β2-adrenergic receptor haplotypes.
Effects of Ile164 polymorphism of beta2-adrenergic receptor gene on coronary artery disease.
Content updated August 2026.
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