Timothy Syndrome

Timothy Syndrome (TS) is a rare and serious genetic disorder characterized by a spectrum of complicated health concerns.

About

Timothy syndrome is known to result from a genetic change in the L-type calcium channel gene CACNA1C on chromosome 12. There are three identified subgroups of Timothy syndrome, each based upon the location of an individual’s specific genetic change. Check out the new Timothy Syndrome Foundation site below.

Check out the new Timothy Syndrome Foundation site below.

Symptoms

Health concerns for Timothy syndrome include:

  • 5An abnormally prolonged repolarization time of the heart (the process of returning the heart to a resting state in preparation for the next heartbeat), as measured by a QT interval of greater than 480 milliseconds to greater than 700 ms, predisposing those who have it to cardiac arrest and sudden death.
  • 5Potential for blood sugar fluctuations which can result in severe life-threatening hypoglycemic events or seizures.
  • 5Physical, mental and social developmental delays, and sometimes autistic spectrum disorders.
  • 5Facial and dental abnormalities are common.

In “Classic” Timothy syndrome, in addition to the concerns listed above, the child has unilateral or bilateral finger syndactyly and/or syndactyly of the 2nd and 3rd toes.

Diagnosis

All forms of Timothy syndrome can be suspected in utero when the fetal heart rate is noted to be slow (fetal bradycardia) or the fetus is found to be in distress. At birth or with the first feeding the neonate can suddenly develop hypoxia (diminished availability of oxygen) and present with cyanosis (a bluish discoloration of the skin). Upon evaluation of bradycardia and/or cyanosis the infant is often found to be in 2:1 AV block (AV or atrio-ventricular block refers to a functional block due to an extremely prolonged ventricular repolarization rather than an AV conduction abnormality), and a prolonged QT interval is always observed.

Within days of birth, the infant often requires a pacemaker in an effort to stabilize the heart rate and reduce the risk for induction of arrhythmias.

All infants in whom Timothy syndrome is suspected should be genetically screened for the CACNA1C gene to confirm the diagnosis.

Genetic testing of the CACNA1C gene for suspected Timothy syndrome is commercially available and recommended. Most pediatric cardiologists would be familiar with protocols for genetic diagnostic testing. Because parental mosaicism might be of concern in families where possible future children would be desired, it is considered prudent for parents to also be specifically screened for identified Timothy syndrome changes as found in their child.

Treatment

Treatment for all forms of Timothy syndrome is complex and is dependent on the severity of the disease in each child. Ventricular arrhythmias (ventricular tachycardia, torsades de pointes and ventricular fibrillation) are present in at least 80%. Treating TS children to improve cardiac survival is of utmost importance. Beta-blockers (Propranolol and Nadolol are considered most effective in treating all types LQTS in children) are generally prescribed. Beta-blockers often further reduce the TS heart rate, thus pacemaker implantation may be needed to control heart rate and ICD implantation is often undertaken.

The congenital heart defects in Timothy syndrome are generally treated with standard procedures. The combination of Beta-blockers, fasting and anesthesia are often known to trigger arrhythmias during in the perioperative period. Because of the cardiac, dental and orthopedic issues in this population, surgery is often necessary. Extreme care must be taken with cardiac monitoring and anesthetic selection. Severe hypoglycemia in this patient population can be an issue when these children are fasting in preparation for surgery. Glucose monitoring and the early use of intravenous glucose is prudent.

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SADS Blog
To read stories of SADS families just like yours, and learn more about life with Timothy Syndrome, visit our blog at SADS.org/blog.

Resources

Timothy Syndrome Brochure