Heart rhythm disorders may have a genetic link. Researchers have identified a gene mutation that appears to interfere with the cardiac conduction system, contributing to lethal heart arrhythmias.

The cardiac conduction system, comprised of specialized cells in the heart walls, regulates the speed and rhythm of the heartbeat by sending electrical signals from the sinoatrial node in the heart’s upper chamber to the lower chambers, causing contraction and blood pumping.

Researchers have identified a gene called Tbx3 that appears to interfere with the development of the cardiac conduction system, potentially causing life threatening heart arrhythmias.

Dr. Anne M. Moon, study author and adjunct professor of pediatrics at the University of Utah School of Medicine, said that the cardiac conduction system is very sensitive to Tbx3 because it is required for the conduction system to develop, mature and function properly. Though Tbx3 has been linked to heart development, its role is not clearly defined.

Researchers used mouse embryos to test their theory, finding that below a critical threshold, mice suffered arrhythmias and could not survive. After the mice were born, they developed arrhythmias or had sudden death as levels of Tbx3 protein were increased.

This occurred because the protein increase impaired the electrical signal in the sinoatrial node and blocked the atrioventricular node, which conducts electrical signals from the atria to the ventricles. The discovery could be another step toward regenerating functional heart tissue.

“There’s a big effort to regenerate heart muscle,” Dr. Moon said. “But if the muscle can’t conduct electrical signals, it’s not going to do any good; we also need to be able to regenerate conduction tissues to regulate that muscle.”

In future research Moon plans to study how the gene regulates the behavior of cells in the cardiac conduction system and whether cells that don’t have enough Tbx3 die or transform into other kinds of cells.

The study was published in the Dec. 26 edition of journal Proceedings of the National Academy of Sciences.