<unk>  <unk>  is an inherited genetic disorder that predisposes those affected to potentially life-threatening abnormal heart rhythms or arrhythmias. The arrhythmias seen in<unk>  typically occur during exercise or at times of emotional stress, and classically take the form of bidirectional<unk><unk>  or<unk>  fibrillation. Those affected may be asymptomatic, but they may also experience blackouts or even sudden cardiac death.<unk>  is caused by genetic mutations affecting proteins that regulate the concentrations of calcium within cardiac muscle cells. The most commonly identified gene is RYR2, which encodes a protein included in an ion channel known as the ryanodine receptor; this channel releases calcium from a cell's internal calcium store, the sarcoplasmic reticulum, during every heartbeat.<unk>  is often diagnosed from an ECG recorded during an exercise tolerance test, but it may also be diagnosed with a genetic test. The condition is treated with medication including beta-adrenoceptor blockers or flecainide, or with surgical procedures including sympathetic denervation and implantation of a defibrillator. It is thought to affect as many as one in ten thousand people and is estimated to cause 15% of all unexplained sudden cardiac deaths in young people. The condition was first defined in 1978, and the underlying genetics were described in 2001.
Catecholaminergic polymorphic ventricular tachycardia
Benign early repolarization
Junctional ectopic tachycardia
Brugada syndrome
Pre-excitation syndrome
Long QT syndrome
Wandering atrial pacemaker
Andersen–Tawil syndrome