Frequently Asked Questions About Andersen-Tawil Syndrome
What is Andersen-Tawil Syndrome and what are the symptoms?
Andersen-Tawil Syndrome (ATS) is a rare inherited disorder which causes episodes of paralysis or weakness. It was only recognized as a separate disorder in 1971.
ATS causes attacks of muscle weakness and irregular heart rhythms. Patients may experience brief episodes of localized weakness in a hand, foot, jaw or limbs or they may experience generalized paralysis. The episodes of weakness often occur during rest after exercise, and they may occur on awakening in the morning. The heart rhythm irregularities include a prolonged QT interval which makes the heart more likely to experience tachycardia (a regular but too rapid heart rate) or dangerous irregular heart rates.
People with ATS often have typical physical characteristics as well. These include large widely spaced eyes, a small jaw, low-set ears, crooked fingers or toes, webbed or fused 2nd and 3rd toes, and small stature.
What causes ATS?
In general the periodic paralyses are caused by abnormalities in the ion channels (especially the sodium, calcium and potassium channels) of the muscle membrane. The ion channels control the movement of sodium, chloride, potassium and calcium across the cell membrane and from one cell compartment to another. This movement of ions produces the electrical 'spark' which allows our muscles to move. All of the ATS mutations identified so far have been in a potassium ion channel. However it is evident that there are other, as yet unidentified, mutations which are responsible for ATS. There may be several variant mutations, producing similar but slightly different forms of the disorder, as occurs in the other forms of periodic paralysis, where several variants of each type have been identified.
Will I pass ATS on to my children and how does inheritance work?
ATS is inherited in an autosomal dominant pattern. The chances that a child of an affected person will inherit the defective gene is 'statistically' 50%, but not all who inherit the gene will have symptoms. The degree to which children are affected may vary from one child to the next. One child may be mildly affected, the next seriously affected and the next unaffected.
What triggers attacks?
Triggers may vary from person to person. Unfortunately this is an area in which food triggers are not as clearly defined as the other types of periodic paralysis, where it is possible to say potassium-rich foods or sweet foods trigger episodes. Since the patient's potassium level may vary from time to time during episodes it may take diligence and real attention to one's body's signals to discover triggers.
Common triggers in the other periodic paralyses include both rest after activity and periods of inactivity (for example; sitting through a long class or church service, especially in a cool room). Sleep is a potent trigger. Going too long without eating is another trigger, as is eating a large meal. Getting chilled is a trigger. Hydrocarbons like gasoline fumes, paint fumes or car exhaust have been reported as triggers by some patients, and are probably best avoided when possible.
How can I determine what causes my attacks?
See How to Determine Episode Triggers
How do I avoid having attacks?
Learn to determine your triggers and try to avoid them whenever possible.
How is ATS treated?
Since individuals vary so much it is difficult, if not impossible, to give guidelines which apply to all ATS patients. Medications which regulate the heart are often prescribed, other treatment depends on the individual and their reaction to potassium. Patients with severe heart rhythm problems may require a pacemaker-like device.
What tests are used to diagnose ATS?
A variety of tests may be used. The presence of episodic paralysis accompanied by heart arrhythmias which include a prolonged QT interval are strongly suggestive of ATS and should be evaluated by a thoroughly experienced team of physicians. The subject of diagnosis is one which is somewhat complex, and is outside the scope of this discussion. For more information see The Exercise EMG and Physician's Sheet: Andersen-Tawil Syndrome.
Can I have a DNA test for ATS?
Genetic testing is not yet available for ATS outside of research programs.
Will I be able to lead a normal life?
Most people with the periodic paralyses lead reasonably normal lives. Many cases of periodic paralysis are mild, and even patients who are more severely affected can manage their symptoms through medication and attention to diet and lifestyle issues. There is no cure, but most patients lead well-rounded and fulfilling lives. There is no denying that some patients have physically-compromised lives, especially patients with a long history of frequent and severe episodes. But many patients are able to remain quite active.
Will my life be cut short by ATS?
Detection and treatment are vital to ATS patients. The primary danger in ATS is from heart arrhythmias. These are treatable.
Will I end up in a wheelchair?
This is a hard question to answer. Permanent muscle weakness is a fact of life for many older patients with periodic paralysis, and activities like climbing stairs and walking long distances may become very fatiguing. Some of our older members use a wheelchair or 'scooter' outside the home, but are mobile and on their feet inside the house. Very few rely on a wheelchair full-time unless their condition is complicated by other problems.
We hope we have answered some of your basic questions about Andersen-Tawil Syndrome. For medical references see our Physician's Sheet: Andersen-Tawil Syndrome.