Familial atrial fibrillation is an

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

heart condition that causes disruptions in 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 A heartbeat is one cardiac cycle of the heart. Heartbeat, heart beat, heartbeats, and heart beats may refer to: Computing *Heartbeat (computing), a periodic signal to indicate normal operation or to synchronize parts of a system *Heartbeat, clus ...

to become fast and irregular.

Cause

It is associated with multiple genes: Mutations in the '' KCNQ1'' gene cause familial atrial fibrillation. The '' KCNE2'' and ''

KCNJ2 The Kir2.1 inward-rectifier potassium channel is a lipid-gated ion channel encoded by the gene. Clinical significance A defect in this gene is associated with Andersen-Tawil syndrome. A mutation in the KCNJ2 gene has also been shown to c ...

'' 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 potassium ions into and out of cells. In heart 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 Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

), 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. Familial atrial fibrillation appears to be inherited in an

pattern, which means the defective gene is located on an

autosome An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in au ...

, and only one copy of the defective gene - inherited from one parent - is sufficient to cause the disorder.

Diagnosis

If untreated, this abnormal heart rhythm can lead to dizziness, chest pain, a sensation of fluttering or pounding in the chest (

palpitations Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac muscle contractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart. Symptoms include a rapi ...

), shortness of breath, or fainting ( syncope). Atrial fibrillation also increases the risk of

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

. 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. Atrial fibrillation is the most common type of sustained abnormal heart rhythm (

arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

), 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.

Treatment

References

External links

{{DEFAULTSORT:Familial Atrial Fibrillation Autosomal dominant disorders Channelopathies Cardiogenetic disorders Rare diseases