Alternative Names
Sudden unexpected nocturnal death syndrome (SUNDS); Sudden unexplained death syndrome; SUDS
Symptoms & Characteristics
Brugada syndrome is a disorder that causes a disruption of the heart's normal rhythm. Brugada syndrome is part of a group of genetic conditions that cause cardiac channelopathies. This condition can lead to uncoordinated electrical activity in the heart's lower chambers (ventricles), 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 individual is resting or asleep.
Brugada syndrome typically becomes apparent in adulthood; however, the signs and symptoms, including sudden death, can occur any time from early infancy to old age. The mean age of sudden death is about 40 years. Brugada syndrome may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of death in babies younger than one 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 during sleep. SUNDS 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 exact condition.
Treatment
Early diagnosis, routine surveillance and treatment of Brugada syndrome may help to manage some of the symptoms and sometimes prevent related problems.
How Common Is It?
Although the exact prevalence of Brugada syndrome is unknown, it is estimated to affect 5 in 10,000 people worldwide. Brugada syndrome occurs more frequently in people of Asian ancestry, particularly in Japanese and Southeast Asian populations.
Although Brugada syndrome affects both men and women, it appears to more common (8 to 10 times) in men. Researchers suspect that higher male levels of testosterone may be responsible for this difference.
Genetics & Inheritance
Mutations in the SCN5A gene on chromosome 3 at the location p21 cause Brugada syndrome. However, mutations in the SCN5A gene have been identified in less than 1/3 of people with Brugada syndrome. In a few families, Brugada syndrome appears to be caused by mutations in one of three other genes: GPD1L, CACNA1C and CACNB2. Other genes that are not yet known or adequate classified are also likely to cause Brugada syndrome.
In many affected people, 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 (called hypercalcemia) or potassium (called hyperkalemia), as well as unusually low potassium levels (called 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 SCN5A mutation.
Brugada syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. An affected person has a 50% chance with each pregnancy to have an affected child.
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.
Genetic Testing
Clinical genetic testing for Brugada syndrome may be available online (over the internet) or through an in person genetic consultation for people who are considered at risk. Use our find a genetic professional directory to locate a trained genetic professional in your area.
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