NOS3 rs1799983: What Your Genotype Means
The rs1799983 variant, commonly known as Glu298Asp, is a genetic change in the NOS3 gene that influences the production of endothelial nitric oxide synthase. This enzyme is critical for regulating vascular tone and has been studied for its potential role in blood pressure response to exercise and cardiovascular health.
What each genotype means
Typical nitric oxide production
This genotype is the most common form of the NOS3 gene, often referred to as the Glu/Glu genotype. Research suggests individuals with this profile may experience a more robust reduction in diastolic blood pressure following endurance training compared to those carrying the T allele.
This is the most common genotype globally, though frequencies vary significantly by ancestry.
Intermediate nitric oxide response
This heterozygous genotype, often called Glu/Asp, represents a mix of the common and minor alleles. Studies indicate that individuals with this genotype may show an intermediate response in blood pressure regulation during exercise compared to the GG and TT groups.
Carried by a significant portion of the population, with the T allele frequency ranging from approximately 10% to 35% depending on ancestral background.
Reduced nitric oxide response
This genotype, often referred to as Asp/Asp, is associated with the minor allele. Some research suggests that individuals with this genotype may experience attenuated vasodilation responses during exercise and potentially smaller reductions in diastolic blood pressure following endurance training programs.
This is the least common genotype, occurring in a smaller percentage of the population compared to GG and GT genotypes.
Understanding the Variant
The rs1799983 variant is a single-nucleotide polymorphism (SNP) located within the NOS3 gene. In scientific literature, it is frequently referred to as Glu298Asp, reflecting a change in the amino acid sequence of the resulting protein where glutamic acid (Glu) is replaced by aspartic acid (Asp) at position 298. This specific change occurs due to a substitution of a guanine (G) base for a thymine (T) base. Because this variant is located in a functional region of the gene, researchers have long investigated whether this structural alteration affects the stability or activity of the enzyme it encodes. It is one of the most widely studied variants in the context of cardiovascular genomics, serving as a focal point for understanding how individual genetic differences might contribute to variations in how our bodies manage blood flow and vascular health.
The Role of the NOS3 Gene
The NOS3 gene provides instructions for creating the enzyme endothelial nitric oxide synthase (eNOS). This enzyme is primarily found in the cells that line the interior surface of blood vessels, known as the endothelium. Its main function is to produce nitric oxide, a signaling molecule that acts as a potent vasodilator. By relaxing the smooth muscle cells surrounding blood vessels, nitric oxide helps to maintain healthy vascular tone, regulate blood pressure, and ensure proper blood flow throughout the body. Because of its central role in cardiovascular homeostasis, the NOS3 gene is considered a key candidate for studies involving exercise physiology and heart health. When the production or function of eNOS is altered, it may influence how effectively the cardiovascular system adapts to physical stress, such as the demands placed on the body during endurance training.
Research and Evidence
Research into rs1799983 has produced mixed and sometimes limited findings regarding its clinical impact. Some studies, such as the HERITAGE Family Study, have explored whether this variant influences how blood pressure changes in response to endurance training. These researchers observed that individuals with different genotypes showed varying degrees of reduction in diastolic blood pressure following a 20-week training program, suggesting a potential link between the variant and exercise-induced vascular adaptation. Other studies have investigated associations between this SNP and conditions like hypertension, insulin resistance, or atherosclerosis. However, the evidence remains complex; while some associations have been reported, they are often modest, and results can vary significantly between different study populations. It is important to note that these findings represent statistical associations in research cohorts and do not imply a direct cause-and-effect relationship for any individual.
Population Frequency
The frequency of the minor allele (T/Asp) for rs1799983 varies across global populations. Data indicates that the T allele frequency is approximately 0.30 to 0.35 in European populations, while it is lower in East Asian populations, typically ranging from 0.10 to 0.15. In populations of African ancestry, the frequency is observed to be around 0.15. These differences highlight the importance of considering ancestral background when interpreting genetic data, as the prevalence of specific genotypes can differ significantly depending on one's heritage.
Interpreting Your Information
Genetic information regarding the NOS3 rs1799983 variant should be viewed as a piece of a much larger puzzle. While the variant is associated with physiological processes like vascular tone, it is not a diagnostic tool for any disease or a definitive predictor of athletic performance. Many factors, including diet, lifestyle, environment, and the interaction of thousands of other genes, play a much larger role in your overall health and fitness. If you are interested in how your genetics might relate to your cardiovascular health or exercise routine, this information is best used as a starting point for a conversation with a healthcare professional. Never use genetic data to make medical decisions or to alter prescribed treatments without consulting your doctor or a qualified pharmacist, as they can provide context based on your full medical history.
How common is this variant?
The minor allele (T) frequency is approximately 0.30-0.35 in Europeans, 0.10-0.15 in East Asians, and 0.15 in African ancestries.
Frequently asked questions
Is rs1799983 a diagnostic test for heart disease?
No, this variant is not a diagnostic test. It is a common genetic variation studied for its potential role in vascular physiology, but it cannot predict or diagnose heart disease.
Does the TT genotype mean I cannot be an endurance athlete?
Absolutely not. Genetic variants like rs1799983 are only one small factor in athletic performance. Training, nutrition, and overall health are far more significant contributors to your fitness capabilities.
Should I take supplements if I have the T allele?
You should never start or change a supplement regimen based on genetic results without consulting your doctor. A healthcare professional can determine if any intervention is appropriate for your specific health needs.
Where can I find more information about my specific genotype?
You can discuss your genetic reports with a certified genetic counselor or your primary care physician. They can help you interpret the information within the context of your personal and family medical history.
Sources & further reading
Educational information only, last refreshed 9/25/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Promoter variant (-786T>C) in the NOS3 gene associated with endothelial nitric oxide synthase expression and cardiovascular risk.
An intronic endothelial nitric oxide synthase polymorphism that influences vascular tone, exercise-induced vasodilation, and aerobic endurance performance.
Commonly studied variant in the endothelial nitric oxide synthase gene, associated with cardiovascular traits.
Endothelial nitric oxide synthase variant implicated in blood flow response and muscle capillarization during aerobic training.
Promoter-adjacent polymorphism affecting endothelial nitric oxide synthase transcription, modulating exercise-induced vasodilation and aerobic trainability.
The Glu298Asp variant in the NOS3 gene is associated with altered nitric oxide production and may influence susceptibility to cardiovascular conditions like hypertension and coronary artery disease.