Andersen–Tawil syndrome
Andersen–Tawil syndrome, also called Andersen syndrome and long QT syndrome 7, is a rare genetic disorder affecting several parts of the body. The three predominant features of Andersen–Tawil syndrome include disturbances of the electrical function of the heart characterised by an abnormality seen on an electrocardiogram (a long QT interval) and a tendency to abnormal heart rhythms, physical characteristics including low-set ears and a small lower jaw, and intermittent periods of muscle weakness known as hypokalaemic periodic paralysis.
| Andersen–Tawil syndrome | |
|---|---|
| Other names | Cardiodysrhythmic potassium-sensitive periodic paralysis, long QT syndrome type 7 |
| This condition affects the QT interval (in blue). | |
| Specialty | Cardiology, Neurology |
| Symptoms | Abnormal heart rhythms, periodic paralysis, characteristic physical features |
| Complications | Sudden death |
| Usual onset | Birth |
| Duration | Lifelong |
| Types | Type 1 (KCNJ2 mutation positive), Type 2 (genetic mutation not identified) |
| Causes | Genetic |
| Diagnostic method | Clinical, genetic testing |
| Differential diagnosis | Romano-Ward syndrome, Jervell and Lange-Nielsen syndrome, Timothy syndrome |
| Treatment | Medication, implantable cardioverter-defibrillator |
| Medication | Flecainide, beta-blockers, acetazolamide |
| Frequency | 1:1,000,000 |
Andersen–Tawil syndrome is inherited in an autosomal dominant pattern. It is caused in most cases by a mutation in the KCNJ2 gene which encodes an ion channel that transports potassium out of cardiac muscle cells. The arrhythmias seen in the condition can be treated with flecainide or beta-blockers, but an implantable defibrillator may sometimes be required. Periodic paralysis can be treated with carbonic anhydrase inhibitors such as acetazolamide. The condition is very rare and is estimated to affect one person in every million. The three groups of features seen in this condition were first described in 1971 by Ellen Andersen, and significant contributions to its understanding were made by Rabi Tawil.