Rett syndrome is a neurological disorder that predominantly affects girls. It is caused by mutations in the MECP2 gene, which is situated on the X-chromosome-linked gene. Rett syndrome patients have severe intellectual, movement, coordination, and communication problems. They also have an increased risk of sudden death, which is generally caused by heart-related problems.
Types of heart problems
People with Rett syndrome have a normal heart size and structure in most cases. However, echocardiogram studies show abnormalities in heart rhythms. The most frequently encountered heart abnormalities that increase the risk of sudden death include:
- Prolonged QT interval, where the heart muscle takes longer than usual to recharge between heartbeats;
- Flat or inverted T waves on the electrocardiogram, which represent the repolarization of the ventricles, or large chambers of the heart;
- Reduced heart-rate variability, or variation in the number of heartbeats per minute;
- Cardiac arrhythmias.
The mechanism by which these abnormalities occur in Rett syndrome patients is not well- understood. Some studies suggest that MECP2 gene mutations cause the autonomic nervous system to be dysfunctional. The autonomic nervous system controls involuntary functions such as heartbeat, breathing, and digestion. The changes to the autonomic nervous system caused by MECP2 mutations are thought to remodel the functioning of the potassium and sodium channels in the heart tissue, contributing to prolonged QT interval, T-wave abnormalities, and cardiac arrhythmias.
Constant monitoring of heart function is essential in Rett syndrome patients because heart problems become worse with time.
The standard therapy to prevent heart problems in Rett syndrome patients is to treat them with β-adrenergic receptor blockers such as Inderal (propranolol). These are medicines that cause the heart to beat more slowly and with less force.
Studies in mice have indicated that sodium channel blockers such as phenytoin may also be effective to overcome heart issues in patients with Rett syndrome, but clinical studies are needed to confirm these findings.
It is recommended that medications that induce QT prolongation should be avoided in Rett syndrome patients. These include cisapride (a prokinetic agent), thioridazine (an antipsychotic), imipramine (an antidepressant), anti-arrhythmic medications such as quinidine, sotalol, and amiodarone, and certain antibiotics including erythromycin and ketoconazole.
Rett Syndrome News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.