Andersen Tawil Syndrome

Andersen Tawil syndrome or ATS is a rare disease characterized by three distinct features that include: periodic paralysis or episodes of muscle weakness, cardiac arrhythmia and distinct facial and skeletal features. However all the three features may not be present in a single patient. Most ATS cases are caused by a mutation in the KCNJ2 gene; other cases result from unknown causes. KCNJ2 gene forms a channel that is responsible for transporting potassium ions into muscle cells. The movement of these ions is essential for maintaining the normal function of muscles. KCNJ2 gene mutations disrupt the structure of the potassium ions and leads to periodic paralysis and irregular heart rhythm.

Periodic paralysis: Anderson Tawil syndrome patients may experience episodes of flaccid paralysis. The lower and the upper limbs normally get affected and the paralysis may remain for short duration or continue for days. The severity and frequency varies from person to person and from episode to episode.

Heart arrhythmia: Anderson Tawil syndrome patients typically present with long QT interval, a disorder of the heart's electrical activity. It can cause sudden, uncontrollable, dangerous arrhythmia in response to exercise or stress.

Distinct Facial or skeletal features: Patients with ATS commonly develop physical abnormalities such as a small lower jaw, dental abnormalities, widely spaced eyes, short stature and curvature of the spine.

Diagnosis and treatment

Examining the clinical features, serum test to assess potassium levels, electrocardiogram to test the heart's electric activity and molecular genetic testing together help in establishing the diagnosis of Anderson Tawil syndrome.

There are no standard protocols laid out for treating ATS because of the rarity of the condition. Treatment of the Anderson Tawil syndrome depends upon the symptoms of the patient. If the patient is suffering from potassium sensitive periodic paralysis, potassium supplements are prescribed to rectify the levels.

However periodic paralysis caused by higher potassium levels resolve on their own in a short while. Of late, drugs known as carbonic anhydrase inhibitors are being used successfully to treat periodic paralysis in individuals with Andersen-Tawil syndrome. Cardiac arrhythmia is normally treated with beta adrenergic blockers and more complicated cases might need pacemakers and implantable defibrillator to prevent sudden cardiac deaths.