What you carry at this position in your DNA and what research says about it.
Heart Rhythm and Rate: 10/10 evidence, 20 publications.
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Sample genotype (not yours): A/A
Typical Heart Rate and Lower Arrhythmia Risk
This genotype is associated with a standard resting heart rate and a lower risk of developing atrial fibrillation.
What this genotype means: Typical resting heart rate; Lower risk of atrial fibrillation; Slightly higher systolic blood pressure.
Sample genotype (not yours): A/G
Slightly Slower Heart Rate and Moderate Arrhythmia Risk
Carrying one copy of the variant allele leads to a slightly lower resting heart rate alongside a modest increase in atrial fibrillation risk.
What this genotype means: Slightly lower resting heart rate; Modestly increased risk of atrial fibrillation; Slightly prolonged PR interval.
Sample genotype (not yours): G/G
Slower Heart Rate but Higher Arrhythmia Risk
This genotype is linked to a significantly slower resting heart rate but carries an increased risk of atrial fibrillation.
What this genotype means: Slower resting heart rate; Increased risk of atrial fibrillation; Prolonged cardiac conduction time.
Gene function and biological role
Gene Function: The MYH6 gene encodes the alpha myosin heavy chain protein, which is a major component of the sarcomere in cardiac muscle cells [1]. This protein is primarily expressed in the heart's atria, where it plays a critical role in generating the mechanical force needed for muscle contraction [1]. It is also essential for the proper development and maintenance of the cardiac conduction system, which regulates the electrical signals driving each heartbeat [2]. Variations in this gene can alter the physical properties of the heart muscle, affecting resting heart rate and susceptibility to arrhythmias [1] [2].
Variant Impact: The rs365990 variant is a missense mutation in exon 25 of the MYH6 gene that alters the encoded protein structure [1]. This genetic change results in the substitution of the amino acid valine with alanine at position 1101 of the alpha myosin heavy chain protein [1]. By altering this residue, the variant subtly modifies the electrical conduction properties of atrial tissue [1]. These changes directly influence resting heart rate, the duration of electrical signals on an electrocardiogram, and the risk of developing common heart rhythm disorders [1] [3].
Key Insight: The G allele of this variant acts as a natural pacemaker decelerator, lowering resting heart rate by nearly one beat per minute per copy, but simultaneously increases the risk of atrial fibrillation.
Location: MYH6. Chromosome 14 · 14q11.2 · 23.4 Mb
Estimated prevalence by population
Global 33.3%; European 39.2%; African 12.7%; East Asian 67.5%; South Asian 47.3%; Americas 39.1%; Ashkenazi 28.9%; Finnish 45.5%; Middle Eastern 28.7%; Amish 48.7%.
Estimated AA genotype frequency.
Global 45.7%; European 46.8%; African 45.9%; East Asian 29.3%; South Asian 43.0%; Americas 46.9%; Ashkenazi 49.7%; Finnish 43.9%; Middle Eastern 49.7%; Amish 42.2%.
Estimated AG genotype frequency.
Global 21.0%; European 14.0%; African 41.4%; East Asian 3.2%; South Asian 9.8%; Americas 14.0%; Ashkenazi 21.4%; Finnish 10.6%; Middle Eastern 21.6%; Amish 9.1%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cardiovascular & Metabolic
Heart Rhythm & Conduction
Resting Heart Rate. Evidence: 10/10. Source: PMID 20062063. Typical.
Atrial Fibrillation. Evidence: 8/10. Source: PMID 34594039. Typical Risk.
Cardiac Conduction. Evidence: 7/10. Source: PMID 20062063. Typical Conduction.
Hypertension
Systolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Slightly Higher.
Diastolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Slightly Lower.
Showing effects for A/G genotype
Resting Heart Rate. Evidence: 10/10. Source: PMID 20062063. Slightly Lower.
Atrial Fibrillation. Evidence: 8/10. Source: PMID 34594039. Slightly Higher Risk.
Cardiac Conduction. Evidence: 7/10. Source: PMID 20062063. Slightly Prolonged.
Systolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Typical.
Diastolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Typical.
Showing effects for G/G genotype
Resting Heart Rate. Evidence: 10/10. Source: PMID 20062063. ~1.8 bpm Lower.
Atrial Fibrillation. Evidence: 8/10. Source: PMID 34594039. Higher Risk.
Cardiac Conduction. Evidence: 7/10. Source: PMID 20062063. Prolonged PR Interval.
Systolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Slightly Lower.
Diastolic Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Slightly Higher.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
This genotype represents the most common genetic profile at this locus, carrying two copies of the reference A allele encoding valine [1]. Individuals with this profile generally exhibit a typical resting heart rate and standard cardiac conduction times, as measured by the PR interval on an electrocardiogram [1]. Because this genotype lacks the G allele, it is associated with a lower baseline risk of developing atrial fibrillation and other atrial arrhythmias [2]. However, it is linked to slightly higher systolic blood pressure and pulse pressure compared to carriers of the variant allele [3]. Overall, this profile represents a balanced cardiovascular baseline with typical heart rhythm dynamics [1] [2].
Typical resting heart rate; Lower risk of atrial fibrillation; Slightly higher systolic blood pressure.
Sample genotype: AG (Heterozygous)
This heterozygous genotype represents a biological middle ground, carrying one copy of the reference A allele (valine) and one copy of the variant G allele (alanine) [1]. Having this single variant copy is associated with a modest decrease in resting heart rate of approximately 0.9 beats per minute [1]. It also results in a slightly prolonged PR interval, indicating a minor delay in the electrical signals traveling through the heart's upper chambers [1]. While a slower resting heart rate is generally considered a marker of cardiovascular efficiency, this genotype also carries a slightly elevated risk of developing atrial fibrillation [2]. Blood pressure traits are typically balanced, with intermediate levels of both systolic and diastolic measurements [3].
Slightly lower resting heart rate; Modestly increased risk of atrial fibrillation; Slightly prolonged PR interval.
Sample genotype: GG (Homozygous)
This genotype carries two copies of the variant G allele, which encodes alanine instead of valine in the cardiac myosin protein [1]. Individuals with this profile experience a pronounced natural slowing of their resting heart rate, averaging nearly two beats per minute lower than the typical population [1]. This deceleration is accompanied by a significantly prolonged PR interval, reflecting slower electrical conduction through the atria [1]. While a slower heart rate is often associated with cardiovascular health, this specific conduction delay increases susceptibility to atrial fibrillation and other atrial tachycardias [2]. Additionally, this genotype is associated with slightly higher diastolic blood pressure but lower systolic blood pressure [3]. It represents a distinct physiological trade-off between a slower resting pulse and altered cardiac rhythm vulnerability [1] [2].
Slower resting heart rate; Increased risk of atrial fibrillation; Prolonged cardiac conduction time.
Variants with shared genetic architecture
rs880315 · CASZ1 Gene · Chr 1 · Blood Pressure Risk
rs6801957 · SCN10A Gene · Chr 3 · Heart Rhythm and Conduction
rs11977526 · TNS3 Gene · Chr 7 · Blood Pressure Regulation
Several common variants modulate heart rate, PR interval and QRS duration.
A rare variant in MYH6 is associated with high risk of sick sinus syndrome.
A cross-population atlas of genetic associations for 220 human phenotypes.
Content updated August 2026.
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