What you carry at this position in your DNA and what research says about it.
Heart Rhythm and Conduction: 9/10 evidence, 25 publications.
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Sample genotype (not yours): T/T
Slower Cardiac Conduction and Higher Brugada Syndrome Risk
This genotype is associated with slower electrical conduction through the heart chambers, leading to longer PR and QRS intervals. It is linked to a higher risk of Brugada syndrome, a rare heart rhythm disorder, but offers relative protection against atrial fibrillation.
What this genotype means: Slower cardiac conduction velocities; Increased risk of Brugada syndrome; Lower risk of atrial fibrillation.
Sample genotype (not yours): C/C
Faster Cardiac Conduction and Higher Atrial Fibrillation Risk
This genotype is associated with faster electrical conduction through the heart, resulting in shorter PR and QRS intervals. It is linked to an increased risk of atrial fibrillation but offers protection against Brugada syndrome.
What this genotype means: Faster cardiac conduction velocities; Increased risk of atrial fibrillation; Lower risk of Brugada syndrome.
Sample genotype (not yours): T/C
Typical Cardiac Conduction and Balanced Arrhythmia Risk
This genotype represents an intermediate state with typical cardiac conduction velocities and balanced risks. It carries a moderate, baseline risk for both Brugada syndrome and atrial fibrillation.
What this genotype means: Typical cardiac conduction intervals; Balanced baseline risk for arrhythmias.
Gene function and biological role
Gene Function: The SCN10A gene encodes a voltage-gated sodium channel subunit historically associated with peripheral sensory neurons. Emerging research demonstrates that SCN10A is also expressed in the heart's conduction system, where it plays a key role in regulating electrical impulses [1]. It forms a functional complex that influences the primary cardiac sodium channel, SCN5A, to coordinate the heartbeat [1]. Genetic variation in this gene is heavily linked to alterations in electrocardiogram measurements like the PR interval and QRS duration [2]. These changes can ultimately influence susceptibility to various heart rhythm disorders [1].
Variant Impact: The rs6801957 variant is located within an intronic enhancer region of the SCN10A gene. This single nucleotide change alters a critical transcription factor binding site, which modulates the expression of cardiac sodium channels [3]. By altering channel expression, the variant directly impacts the cardiac sodium current and conduction velocity [3]. This molecular shift leads to measurable changes in electrocardiogram parameters and susceptibility to arrhythmias [1].
Key Insight: This variant acts as a genetic volume slider for cardiac sodium channels, where one allele speeds up heart conduction but raises atrial fibrillation risk, while the other slows conduction and increases Brugada syndrome risk.
Location: SCN10A. Chromosome 3 · 3p22.2 · 38.7 Mb
Estimated prevalence by population
Global 12.3%; European 16.3%; African 2.4%; East Asian 4.3%; South Asian 13.2%; Americas 15.5%; Ashkenazi 15.8%; Finnish 21.6%; Middle Eastern 16.7%; Amish 20.3%.
Estimated TT genotype frequency.
Global 41.7%; European 48.2%; African 26.4%; East Asian 32.9%; South Asian 46.3%; Americas 47.7%; Ashkenazi 47.9%; Finnish 49.7%; Middle Eastern 48.3%; Amish 49.5%.
Estimated TC genotype frequency.
Global 46.1%; European 35.5%; African 71.2%; East Asian 62.8%; South Asian 40.5%; Americas 36.7%; Ashkenazi 36.3%; Finnish 28.7%; Middle Eastern 35.0%; Amish 30.2%.
Estimated CC genotype frequency.
Showing effects for T/T genotype
Cardiovascular & Metabolic
Heart Rhythm & Conduction
Atrial Fibrillation. Evidence: 9/10. Source: PMID 36653681. Lower Risk.
Brugada Syndrome. Evidence: 8/10. Source: PMID 35210625. ~2.46x Higher Risk.
Cardiac Conduction. Evidence: 8/10. Source: PMID 21076409. Slower Conduction.
Heart Rate. Evidence: 8/10. Source: PMID 39024449. Slightly Lower.
Showing effects for C/C genotype
Atrial Fibrillation. Evidence: 9/10. Source: PMID 36653681. Increased Risk.
Brugada Syndrome. Evidence: 8/10. Source: PMID 35210625. Lower Risk.
Cardiac Conduction. Evidence: 8/10. Source: PMID 21076409. Faster Conduction.
Heart Rate. Evidence: 8/10. Source: PMID 39024449. Slightly Higher.
Showing effects for T/C genotype
Atrial Fibrillation. Evidence: 9/10. Source: PMID 36653681. Typical Risk.
Brugada Syndrome. Evidence: 8/10. Source: PMID 35210625. Typical Risk.
Cardiac Conduction. Evidence: 8/10. Source: PMID 21076409. Typical Conduction.
Heart Rate. Evidence: 8/10. Source: PMID 39024449. Typical.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Slower electrical conduction in the heart is a hallmark of this genotype, characterized by prolonged PR and QRS intervals on an electrocardiogram [1]. The T allele reduces the activity of a cardiac enhancer, which decreases the expression of cardiac sodium channels and slows down the electrical impulses driving each heartbeat [2]. This conduction slowing is associated with a significantly higher risk of Brugada syndrome, a rare but serious arrhythmia of the lower heart chambers [2]. However, this same electrical slowing appears to provide relative protection against atrial fibrillation, a common arrhythmia of the upper chambers [3]. Individuals with this genotype also tend to have a slightly lower resting heart rate [4]. Maintaining regular cardiovascular checkups is a prudent way to monitor overall heart health.
Slower cardiac conduction velocities; Increased risk of Brugada syndrome; Lower risk of atrial fibrillation.
Sample genotype: CC (Homozygous)
Rapid electrical conduction through the heart chambers characterizes this genotype, leading to shorter PR and QRS intervals on an electrocardiogram [1]. The C allele maintains high enhancer activity, promoting robust expression of cardiac sodium channels and swift electrical transmission [2]. While this rapid conduction protects against Brugada syndrome, it significantly increases susceptibility to atrial fibrillation, a common upper-chamber arrhythmia [3]. The rapid electrical signaling can make the atria more prone to chaotic, irregular rhythms [3]. Additionally, this genotype is associated with a slightly higher resting heart rate and a higher overall risk of cardiac arrhythmias [4]. Managing cardiovascular risk factors like high blood pressure and alcohol intake can help mitigate the risk of developing atrial fibrillation.
Faster cardiac conduction velocities; Increased risk of atrial fibrillation; Lower risk of Brugada syndrome.
Sample genotype: TC (Heterozygous)
Balanced electrical conduction is typical for this intermediate genotype, which carries one copy of each allele. Electrocardiogram parameters, such as the PR and QRS intervals, generally fall within the normal range [1]. Because this genotype possesses both the conduction-slowing T allele and the conduction-speeding C allele, the opposing electrical effects tend to balance out [1]. The risk for Brugada syndrome is intermediate, avoiding the higher risk associated with the T/T genotype [2]. Similarly, the risk for atrial fibrillation is moderate, lying between the protective T/T state and the higher-risk C/C state [3]. Overall heart rate and other cardiovascular measurements typically remain within standard baseline ranges [4]. Standard healthy lifestyle choices and routine medical care are sufficient for maintaining heart health.
Typical cardiac conduction intervals; Balanced baseline risk for arrhythmias.
Variants with shared genetic architecture
rs10428132 · SCN10A Gene · Chr 3 · Cardiac Arrhythmia Risk
rs6795970 · SCN10A Gene · Chr 3 · Heart Rhythm and Pain Sensitivity
rs6800541 · SCN10A Gene · Chr 3 · Heart Rhythm and Conduction
Common variants in 22 loci are associated with QRS duration and cardiac ventricular conduction.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Content updated August 2026.
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