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Questions and Answers
What gene encodes Nav1.5?
What gene encodes Nav1.5?
Which syndrome is associated with gain-of-function mutations in SCN5A?
Which syndrome is associated with gain-of-function mutations in SCN5A?
What characteristic feature can occur spontaneously in Brugada syndrome?
What characteristic feature can occur spontaneously in Brugada syndrome?
Which of the following is a known result of gain-of-function mutations in SCN5A in Type 3 Long QT syndrome?
Which of the following is a known result of gain-of-function mutations in SCN5A in Type 3 Long QT syndrome?
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What recent gene was identified as being responsible for Brugada syndrome?
What recent gene was identified as being responsible for Brugada syndrome?
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What effect do sodium-channel blockers have on Brugada syndrome?
What effect do sodium-channel blockers have on Brugada syndrome?
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What technique is used for quantifying electrophysiological changes in whole tissues or hearts?
What technique is used for quantifying electrophysiological changes in whole tissues or hearts?
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Which syndrome is NOT listed as a genetic polymorphism associated with SCN5A?
Which syndrome is NOT listed as a genetic polymorphism associated with SCN5A?
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What is the primary function of Nav1.5 in the human heart?
What is the primary function of Nav1.5 in the human heart?
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Which statement best describes Nav1.5?
Which statement best describes Nav1.5?
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What clinical implications can arise from genetic polymorphisms in SCN5A?
What clinical implications can arise from genetic polymorphisms in SCN5A?
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Which experimental technique is appropriate to explore cardiac electrophysiology?
Which experimental technique is appropriate to explore cardiac electrophysiology?
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What effect does the familial atrial fibrillation mutation M1875T-SCN5A have on sodium current?
What effect does the familial atrial fibrillation mutation M1875T-SCN5A have on sodium current?
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Which publication is associated with new Brugada syndrome risk loci?
Which publication is associated with new Brugada syndrome risk loci?
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What is NOT a characteristic of Nav1.5?
What is NOT a characteristic of Nav1.5?
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What is one of the biophysical properties of Nav1.5?
What is one of the biophysical properties of Nav1.5?
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What is a consequence of using anti-arrhythmic drugs with a narrow therapeutic window?
What is a consequence of using anti-arrhythmic drugs with a narrow therapeutic window?
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Which polymorphism in SCN5A has been associated with increased sensitivity to propafenone?
Which polymorphism in SCN5A has been associated with increased sensitivity to propafenone?
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What major adverse event is associated with the use of flecainide?
What major adverse event is associated with the use of flecainide?
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What did the study by Echt et al. (1991) indicate about flecainide?
What did the study by Echt et al. (1991) indicate about flecainide?
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What characteristic of SCN5A is mentioned in relation to familial atrial fibrillation?
What characteristic of SCN5A is mentioned in relation to familial atrial fibrillation?
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What potential effect does propafenone have on ECG patterns?
What potential effect does propafenone have on ECG patterns?
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In MAPRE KO hiPSC-CMs, what changes were observed?
In MAPRE KO hiPSC-CMs, what changes were observed?
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Natural differences in biophysical properties of SCN5A are noted between which regions?
Natural differences in biophysical properties of SCN5A are noted between which regions?
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Study Notes
Nav1.5 Biophysical Properties
- Nav1.5 is the pore-forming subunit of the voltage-gated sodium channel in the human heart.
- Nav1.5 is encoded by the SCN5A gene.
- Nav1.5 is responsible for generating the sodium current (INa) in the heart.
Nav1.5 Gating
- Nav1.5 undergoes a series of transitions (gating) to allow sodium ions to flow through the channel.
- These transitions include activation, inactivation, and recovery from inactivation.
Genetic Polymorphisms in SCN5A
- Mutations in SCN5A can lead to various cardiac disorders.
- Long QT Syndrome (LQTS) is caused by gain-of-function mutations in SCN5A, resulting in prolonged action potential duration (APD) and QT interval.
- Brugada Syndrome (BrS) is caused by loss-of-function mutations in SCN5A.
- Early Repolarisation Syndrome, Congenital Sick Sinus Syndrome, Familial Atrial Fibrillation, and Sudden Infant Death Syndrome are other disorders associated with SCN5A polymorphisms.
Brugada Syndrome
- BrS is characterized by a unique ECG pattern and an increased risk of sudden cardiac death.
- New gene, MAPRE2, has been identified as a risk factor for BrS.
- MAPRE2 deficiency leads to reductions in conduction velocity, action potential upstroke velocity, sodium current, and prolonged action potential duration.
Optical Mapping for Cardiac Electrophysiology
- Optical mapping uses fluorescent dyes to visualize and analyze electrical activity in heart cells and tissues.
- It offers a powerful tool for studying arrhythmias and the effects of anti-arrhythmic drugs.
Anti-Arrhythmic Drugs and SCN5A
- Anti-arrhythmic drugs can be challenging to use due to narrow therapeutic windows and potential for pro-arrhythmia.
- Flecainide and propafenone are anti-arrhythmic drugs that can cause adverse events, including prolonged QRS duration, BrS, and cardiogenic shock.
- Flecainide can increase mortality compared to placebo in patients with ventricular arrhythmia.
- Propafenone can induce a BrS-like pattern in individuals with specific SCN5A polymorphisms.
- Certain SCN5A mutations can decrease sensitivity to flecainide, suggesting individual variability in drug responses.
Biophysical Diversity in SCN5A
- There are naturally occurring differences in the biophysical properties of Nav1.5 between left ventricular and right ventricular myocardium.
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Description
This quiz explores the biophysical properties and gating mechanisms of the Nav1.5 sodium channel in the heart. It also covers the genetic polymorphisms in the SCN5A gene and their association with various cardiac disorders such as Long QT Syndrome and Brugada Syndrome. Test your knowledge on how these elements contribute to cardiac function and dysfunction.
