Brugada Syndrome

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This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/condition/brugada-syndrome

Brugada syndrome is a condition that causes a disruption of the heart's normal rhythm. Specifically, this disorder can lead to irregular heartbeats in the heart's lower chambers (ventricles), which is an abnormality called ventricular arrhythmia. If untreated, the irregular heartbeats can cause fainting (syncope), seizures, difficulty breathing, or sudden death. These complications typically occur when an affected person is resting or asleep.

genetic conditions

1. Introduction

Brugada syndrome usually becomes apparent in adulthood, although it can develop any time throughout life. Signs and symptoms related to arrhythmias, including sudden death, can occur from early infancy to late adulthood. Sudden death typically occurs around age 40. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of death in babies younger than 1 year. SIDS is characterized by sudden and unexplained death, usually during sleep.

Sudden unexplained nocturnal death syndrome (SUNDS) is a condition characterized by unexpected cardiac arrest in young adults, usually at night during sleep. This condition was originally described in Southeast Asian populations, where it is a major cause of death. Researchers have determined that SUNDS and Brugada syndrome are the same disorder.

2. Frequency

The exact prevalence of Brugada syndrome is unknown, although it is estimated to affect 5 in 10,000 people worldwide. This condition occurs much more frequently in people of Asian ancestry, particularly in Japanese and Southeast Asian populations.

Although Brugada syndrome affects both men and women, the condition appears to be 8 to 10 times more common in men. Researchers suspect that testosterone, a sex hormone present at much higher levels in men, may account for this difference.

3. Causes

Brugada syndrome can be caused by mutations in one of several genes. The most commonly mutated gene in this condition is SCN5A, which is altered in approximately 30 percent of affected individuals. This gene provides instructions for making a sodium channel, which normally transports positively charged sodium atoms (ions) into heart muscle cells. This type of ion channel plays a critical role in maintaining the heart's normal rhythm. Mutations in the SCN5A gene alter the structure or function of the channel, which reduces the flow of sodium ions into cells. A disruption in ion transport alters the way the heart beats, leading to the abnormal heart rhythm characteristic of Brugada syndrome.

Mutations in other genes can also cause Brugada syndrome. Together, these other genetic changes account for less than two percent of cases of the condition. Some of the additional genes involved in Brugada syndrome provide instructions for making proteins that ensure the correct location or function of sodium channels in heart muscle cells. Proteins produced by other genes involved in the condition form or help regulate ion channels that transport calcium or potassium into or out of heart muscle cells. As with sodium channels, proper flow of ions through calcium and potassium channels in the heart muscle helps maintain a regular heartbeat. Mutations in these genes disrupt the flow of ions, impairing the heart's normal rhythm.

In affected people without an identified gene mutation, the cause of Brugada syndrome is often unknown. In some cases, certain drugs may cause a nongenetic (acquired) form of the disorder. Drugs that can induce an altered heart rhythm include medications used to treat some forms of arrhythmia, a condition called angina (which causes chest pain), high blood pressure, depression, and other mental illnesses. Abnormally high blood levels of calcium (hypercalcemia) or potassium (hyperkalemia), as well as unusually low potassium levels (hypokalemia), also have been associated with acquired Brugada syndrome. In addition to causing a nongenetic form of this disorder, these factors may trigger symptoms in people with an underlying mutation in SCN5A or another gene.

4. Inheritance

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition. Other cases may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family.

5. Other Names for This Condition

bangungut
idiopathic ventricular fibrillation, Brugada type
Pokkuri death syndrome
sudden unexpected nocturnal death syndrome
sudden unexplained death syndrome
SUDS
SUNDS

References

Antzelevitch C, Brugada P, Borggrefe M, Brugada J, Brugada R, Corrado D,Gussak I, LeMarec H, Nademanee K, Perez Riera AR, Shimizu W, Schulze-Bahr E, Tan H, Wilde A. Brugada syndrome: report of the second consensus conference. HeartRhythm. 2005 Apr;2(4):429-40. Review. Erratum in: Heart Rhythm. 2005Aug;2(8):905. Citation on PubMed
Antzelevitch C. Brugada syndrome: clinical, genetic, molecular, cellular andionic aspects. Expert Rev Cardiovasc Ther. 2003 Jul;1(2):177-85. Review. Citation on PubMed
Brugada P, Brugada J. Right bundle branch block, persistent ST segmentelevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol. 1992 Nov 15;20(6):1391-6. Citation on PubMed
Brugada R, Campuzano O, Sarquella-Brugada G, Brugada J, Brugada P. Brugadasyndrome. Methodist Debakey Cardiovasc J. 2014 Jan-Mar;10(1):25-8. Review. Citation on PubMed or Free article on PubMed Central
Brugada R, Campuzano O, Sarquella-Brugada G, Brugada P, Brugada J, Hong K.Brugada Syndrome. 2005 Mar 31 [updated 2016 Nov 17]. In: Adam MP, Ardinger HH,Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, editors. GeneReviews®[Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020. Availablefrom http://www.ncbi.nlm.nih.gov/books/NBK1517/ Citation on PubMed
Crotti L, Marcou CA, Tester DJ, Castelletti S, Giudicessi JR, Torchio M,Medeiros-Domingo A, Simone S, Will ML, Dagradi F, Schwartz PJ, Ackerman MJ.Spectrum and prevalence of mutations involving BrS1- through BrS12-susceptibilitygenes in a cohort of unrelated patients referred for Brugada syndrome genetictesting: implications for genetic testing. J Am Coll Cardiol. 2012 Oct9;60(15):1410-8. doi: 10.1016/j.jacc.2012.04.037. Epub 2012 Jul 25. Citation on PubMed or Free article on PubMed Central
Francis J, Antzelevitch C. Brugada syndrome. Int J Cardiol. 2005 May25;101(2):173-8. Review. Citation on PubMed or Free article on PubMed Central
Juang JM, Huang SK. Brugada syndrome--an under-recognized electrical diseasein patients with sudden cardiac death. Cardiology. 2004;101(4):157-69. Epub 2004 Feb 12. Review. Citation on PubMed
Le Scouarnec S, Karakachoff M, Gourraud JB, Lindenbaum P, Bonnaud S, PorteroV, Duboscq-Bidot L, Daumy X, Simonet F, Teusan R, Baron E, Violleau J, Persyn E, Bellanger L, Barc J, Chatel S, Martins R, Mabo P, Sacher F, Haïssaguerre M, KyndtF, Schmitt S, Bézieau S, Le Marec H, Dina C, Schott JJ, Probst V, Redon R.Testing the burden of rare variation in arrhythmia-susceptibility genes provides new insights into molecular diagnosis for Brugada syndrome. Hum Mol Genet. 2015May 15;24(10):2757-63. doi: 10.1093/hmg/ddv036. Epub 2015 Feb 3. Citation on PubMed
Li A, Behr ER. Brugada syndrome: an update. Future Cardiol. 2013Mar;9(2):253-71. doi: 10.2217/fca.12.82. Review. Citation on PubMed
Modell SM, Lehmann MH. The long QT syndrome family of cardiac ionchannelopathies: a HuGE review. Genet Med. 2006 Mar;8(3):143-55. Review. Citation on PubMed
Shimizu W, Aiba T, Kamakura S. Mechanisms of disease: current understandingand future challenges in Brugada syndrome. Nat Clin Pract Cardiovasc Med. 2005Aug;2(8):408-14. Review. Citation on PubMed
Shimizu W. Acquired forms of the Brugada syndrome. J Electrocardiol. 2005Oct;38(4 Suppl):22-5. Review. Citation on PubMed
Vatta M, Dumaine R, Varghese G, Richard TA, Shimizu W, Aihara N, Nademanee K, Brugada R, Brugada J, Veerakul G, Li H, Bowles NE, Brugada P, Antzelevitch C,Towbin JA. Genetic and biophysical basis of sudden unexplained nocturnal deathsyndrome (SUNDS), a disease allelic to Brugada syndrome. Hum Mol Genet. 2002 Feb 1;11(3):337-45. Citation on PubMed

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Subjects: Genetics & Heredity

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Peter Tang

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Table of Contents

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1. Introduction

2. Frequency

3. Causes

4. Inheritance

5. Other Names for This Condition

References

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1. Introduction

2. Frequency

3. Causes

3.1. The genes associated with Brugada syndrome

4. Inheritance

5. Other Names for This Condition

References