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Brugada syndrome

Other Names: Sudden Unexpected Nocturnal Death Syndrome


Brugada syndrome is a genetic condition characterized by a high risk of ventricular arrhythmias and sudden cardiac death. It is most commonly caused by mutations in the SCN5A gene which makes a protein called sodium channel protein type 5, subunit alpha.

Characteristics of Brugada syndrome
Brugada syndrome (BrS) is a condition associated with a high risk of ventricular arrhythmias or sudden cardiac death. A ventricular arrhythmia is an abnormal heart rate or abnormal heart rhythm that originates in the lower chambers, or ventricles, of the heart. BrS usually presents during adulthood, however the age of diagnosis can range from infancy to 85 years of age. Unexplained fainting (syncope) and temporary loss of consciousness are commonly the first symptoms of the condition. These can occur when someone is resting, sleeping, or has a high fever. Sudden death can occur at any age but the average is 40 years. Other presentations of BrS can include Sudden Infant Death syndrome (SIDS) and in certain populations, Sudden Unexpected Nocturnal Death Syndrome (SUNDS). BrS occurs more frequently in males, but can also affect females.
BrS is recognized when an individual has a certain type of EKG or electrocardiogram pattern, called Type 1. An EKG/ECG is a test that checks for problems with the electrical activity of the heart. BrS is thought to be responsible for 4-12% of unexpected sudden deaths and for up to 20% of all sudden death in individuals with a normal heart.

Diagnosis/Testing
Most individuals with BrS have a change or mutation in one of eight genes: SCN5A, GPD1L, CACNA1C, CACNB2, SCN1B, KCNE3, SCN3B, and HCN4. Approximately 15-30% of individuals diagnosed with BrS have a change or mutation in one of their SCN5A genes which stands for sodium channel protein type 5, subunit alpha. This gene makes a sodium channel in the heart that is important in keeping a normal rate of heartbeat or rhythm. Mutations in the SCN5A gene are thought to interfere with the sodium channels function.

Management/Surveillance
Since individuals with BrS are at risk for are at risk to have ventricular arrhythmia, cardiac arrest or sudden cardiac death, it is very important for them to be evaluated by and receive care from a care provider (e.g., a doctor) who is familiar with these conditions and their treatment. Some individuals with BrS and a history of fainting or heart attack may require an ICD (implantable cardioverter defibrillator). An ICD is a small device placed under the skin that detects arrhythmias and keeps track of the heart rhythm. It can correct an abnormal beat in the heart.
Individuals who have BrS should avoid certain medications including anesthetics, antidepressant drugs, and antipsychotic drugs with sodium-blocking effects, as well as high fevers.

Mode of inheritance
BrS is inherited in an autosomal dominant pattern. This means inheriting one SCN5A mutation is enough for an individual to be affected and show signs of BrS. The mutation can be inherited from an affected parent or it can occur brand new (de novo) in an affected child. While the vast majority of individuals with BrS inherit the SCN5A mutation from a parent, in a minority of cases, the mutation newly arose in them by chance.

Risk to family members
The risk to family members depends on whether or not the individual with BrS has a parent affected with BrS. If a parent also has BrS, the risk of having a child with BrS is 50% with each pregnancy. If a parent does not have BrS, the risk of other siblings being affected is very low.

Special considerations
None

Resources
Brugada Syndrome
Sudden Arrhythmia Death Syndromes
BrugadaDrugs: Aid to physicians who treat individuals with BrS and an aid to individuals with BrS
Mayo Clinic Health: Brugada syndrome

References
Berne, P. et al. (2012)."Brugada syndrome." Circulation Journal 76(7): 1563-1571.
Brugada R, Campuzano O, Brugada P, Brugada J, Hong K. (Updated 16 August 2012). Brugada Syndrome. In: GeneReviews at GeneTests Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997-2013. Available at http://www.ncbi.nlm.nih.gov/books/NBK1517/. Accessed [11/20/2012].
Veerakul, G. et al. (2012)."Brugada syndrome: two decades of progress." Circulation Journal 76(12): 2713-2722.
Vohra, J. (2011)."Diagnosis and management of Brugada Syndrome." Heart, lung & circulation 20(12): 751-756.

Created:05/2013

Updated:mm/yyyy

Created by:Karin M. Dent, MS, LCGC

Edited by:Seema Jamal, MSc, LCGC



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