<unk>  <unk>  is a genetic disorder in which the electrical activity within the heart is abnormal. It increases the risk of abnormal heart rhythms and sudden cardiac death. Those affected may have episodes of passing out. The abnormal heart rhythms seen in those with<unk>  often occur at rest. They may be triggered by a fever. About a quarter of those with<unk>  have a family member who also has the condition. Some cases may be due to a new genetic mutation or certain medications. The most commonly involved gene is SCN5A which encodes the cardiac sodium channel. Diagnosis is typically by electrocardiogram (ECG), however, the abnormalities may not be consistently present. Medications such as ajmaline may be used to reveal the ECG changes. Similar ECG patterns may be seen in certain electrolyte disturbances or when the blood supply to the heart has been reduced. There is no cure for<unk> . Those at higher risk of sudden cardiac death may be treated using an implantable cardioverter defibrillator (ICD). In those without symptoms the risk of death is much lower, and how to treat this group is less clear. Isoproterenol may be used in the short term for those who have frequent life-threatening abnormal heart rhythms, while quinidine may be used longer term. Testing people's family members may be recommended. The condition affects between 1 and 30 per 10,000 people. It is more common in males than females and in those of Asian descent. The onset of symptoms is usually in adulthood. It is named after the Spanish cardiologists Pedro and Josep<unk>  who described the condition in 1992. Their brother Ramon<unk>  was the first to describe one potential genetic cause in 1998.
Brugada syndrome
Arrhythmogenic cardiomyopathy
Pacak–Zhuang syndrome
Duchenne muscular dystrophy
Woodhouse–Sakati syndrome
Romano–Ward syndrome
Pascual-Castroviejo syndrome type 1
Catecholaminergic polymorphic ventricular tachycardia