Familial atrial fibrillation

Familial atrial fibrillation
Classification and external resources
OMIM	608583
DiseasesDB	34356

Familial atrial fibrillation is an autosomal dominant 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 to become fast and irregular.

Diagnosis

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. 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), 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.

Cause

Familial atrial fibrillation has an autosomal dominant pattern of inheritance.

It is associated with multiple genes:

Type	OMIM	Gene	Locus
ATFB1	608583	?	10q22-q24
ATFB2	608988	?	6q
ATFB3	607554	KCNQ1	11
ATFB4	611493	KCNE2	21
ATFB5	611494	?	4q25
ATFB6	612201	NPPA	1p36-p35
ATFB7	612240	KCNA5	12p13
ATFB8	613055	?	16q22

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 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), 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 autosomal dominant pattern, which means the defective gene is located on an autosome, and only one copy of the defective gene - inherited from one parent - is sufficient to cause the disorder.

External links

National Library of Medicine. Familial atrial fibrillation

Cardiovascular disease I00–I52, 390–429

Ischaemic

Coronary disease	Coronary artery disease (CAD) Coronary artery aneurysm Coronary artery dissection Coronary thrombosis Coronary vasospasm Myocardial bridge

Active ischemia	Angina pectoris Prinzmetal's angina Stable angina Acute coronary syndrome Myocardial infarction Unstable angina

Sequelae	hours Hibernating myocardium Myocardial stunning days Myocardial rupture weeks Aneurysm of heart / Ventricular aneurysm Dressler syndrome

Layers

Pericardium

Myocardium

Endocardium /
valves

Endocarditis	infective endocarditis Subacute bacterial endocarditis non-infective endocarditis Libman–Sacks endocarditis Nonbacterial thrombotic endocarditis

Valves	mitral regurgitation prolapse stenosis aortic stenosis insufficiency tricuspid stenosis insufficiency pulmonary stenosis insufficiency

Conduction /
arrhythmia

Bradycardia

Tachycardia
(paroxysmal and sinus)

Supraventricular	Atrial Multifocal Junctional AV nodal reentrant Junctional ectopic

Ventricular	Accelerated idioventricular rhythm Catecholaminergic polymorphic Torsades de pointes

Premature contraction

Pre-excitation syndrome

Flutter / fibrillation

Other / ungrouped

Other

Diseases of ion channels

Calcium channel

Voltage-gated	CACNA1A Familial hemiplegic migraine 1 Episodic ataxia 2 Spinocerebellar ataxia type-6 CACNA1C Timothy syndrome Brugada syndrome 3 Long QT syndrome 8 CACNA1F Ocular albinism 2 CSNB2A CACNA1S Hypokalemic periodic paralysis 1 Thyrotoxic periodic paralysis 1 CACNB2 Brugada syndrome 4

Ligand gated	RYR1 Malignant hyperthermia Central core disease RYR2 CPVT1 ARVD2

Sodium channel

Voltage-gated	SCN1A Familial hemiplegic migraine 3 GEFS+ 2 Febrile seizure 3A SCN1B Brugada syndrome 6 GEFS+ 1 SCN4A Hypokalemic periodic paralysis 2 Hyperkalemic periodic paralysis Paramyotonia congenita Potassium-aggravated myotonia SCN4B Long QT syndrome 10 SCN5A Brugada syndrome 1 Long QT syndrome 3 SCN9A Erythromelalgia Febrile seizure 3B Paroxysmal extreme pain disorder Congenital insensitivity to pain

Constitutively active	SCNN1B/SCNN1G Liddle's syndrome SCNN1A/SCNN1B/SCNN1G Pseudohypoaldosteronism 1AR

Potassium channel

Voltage-gated	KCNA1 Episodic ataxia 1 KCNA5 Familial atrial fibrillation 7 KCNC3 Spinocerebellar ataxia type-13 KCNE1 Jervell and Lange-Nielsen syndrome Long QT syndrome 5 KCNE2 Long QT syndrome 6 KCNE3 Brugada syndrome 5 KCNH2 Short QT syndrome KCNQ1 Jervell and Lange-Nielsen syndrome Romano–Ward syndrome Short QT syndrome Long QT syndrome 1 Familial atrial fibrillation 3 KCNQ2 BFNS1

Inward-rectifier	KCNJ1 Bartter syndrome 2 KCNJ2 Andersen–Tawil syndrome Long QT syndrome 7 Short QT syndrome) KCNJ11 TNDM3 KCNJ18 Thyrotoxic periodic paralysis 2

Chloride channel

TRP channel

TRPC6
- FSGS2
TRPML1
- Mucolipidosis type IV

Connexin

Porin

AQP2
- Nephrogenic diabetes insipidus 2

See also: ion channels

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