Familial Atrial Fibrillation
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What is familial atrial fibrillation?Familial atrial fibrillation is an inherited condition that disrupts the heart's normal rhythm. This condition is characterized by uncoordinated electrical activity in the heart's upper chambers (the atria), which causes the heartbeat to become fast and irregular. If untreated, this abnormal heart rhythm can lead to dizziness, chest pain, a sensation of fluttering or pounding in the chest (palpitations), shortness of breath, or fainting (syncope). Atrial fibrillation also increases the risk of stroke and sudden death. Complications of familial atrial fibrillation can occur at any age, although some people with this heart condition never experience any health problems associated with the disorder. How common is familial atrial fibrillation?Atrial fibrillation is the most common type of sustained abnormal heart rhythm (arrhythmia), affecting more than 3 million people in the United States. The risk of developing this irregular heart rhythm increases with age. The incidence of the familial form of atrial fibrillation is unknown; however, recent studies suggest that up to 30 percent of all people with atrial fibrillation may have a history of the condition in their family. What genes are related to familial atrial fibrillation?Mutations in the KCNQ1 gene cause familial atrial fibrillation. The KCNE2 and KCNJ2 genes are associated with familial atrial fibrillation. A small percentage of all cases of familial atrial fibrillation are associated with changes in the KCNE2, KCNJ2, and KCNQ1 genes. These genes provide instructions for making proteins that act as channels across the cell membrane. These channels transport positively charged atoms (ions) of potassium into and out of cells. In heart (cardiac) muscle, the ion channels produced from the KCNE2, KCNJ2, and KCNQ1 genes play critical roles in maintaining the heart's normal rhythm. Mutations in these genes have been identified in only a few families worldwide. These mutations increase the activity of the channels, which changes the flow of potassium ions between cells. This disruption in ion transport alters the way the heart beats, increasing the risk of syncope, stroke, and sudden death. Most cases of atrial fibrillation are not caused by mutations in a single gene. This condition is often related to structural abnormalities of the heart or underlying heart disease. Additional risk factors for atrial fibrillation include high blood pressure (hypertension), diabetes mellitus, a previous stroke, or an accumulation of fatty deposits and scar-like tissue in the lining of the arteries (atherosclerosis). Although most cases of atrial fibrillation are not known to run in families, studies suggest that they may arise partly from genetic risk factors. Researchers are working to determine which genetic changes may influence the risk of atrial fibrillation. How do people inherit familial atrial fibrillation?Familial atrial fibrillation appears to be inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
Source: National Institutes of Health
Study results from University of Barcelona broaden understanding of sudden death
2007 JUN 26 -- Research findings, "Channelopathies: a new category of diseases causing sudden death," are discussed in a new report. According to recent research published in the journal Herz, "Identification of familial forms of different diseases has provided a unique opportunity to study how changes in the structure of a gene create a dysfunction in the physiology of the resulting protein. Changes in the genes encoding for ion channels produce modifications in the function of the channel." "Changes in the sodium channel are responsible for long QT syndrome, Brugada syndrome and conduction defects. Changes in the potassium channels have been related to long QT syndrome, short QT syndrome and familial atrial fibrillation," wrote J. Brugada and colleagues, University of Barcelona. The researchers concluded: "Relating genetic modification and dysfunction allows to study the substrate for a disease, understand the physiopathologic mechanism and look for appropriate therapies." Brugada and colleagues published their study in Herz (Channelopathies: a new category of diseases causing sudden death. Herz, 2007;32(3):185-91). For additional information, contact J. Brugada, University of Barcelona, Thorax Institute, Hospital Clinic, Spain. The publisher's contact information for the journal Herz is: Urban & Vogel, Neumarkter Strasse 43, D-81673 Munich, Germany. Keywords: Spain, Sudden Death. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2007, Life Science Weekly via NewsRx.com.
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