The human heart is powered by a group of specialized cells that direct the ventricles to retract and pump blood, creating a life-sustaining rhythm. If the group of cells, called the cardiac conduction system (CCS), stops functioning correctly, the heart can beat too fast or too slow, a potentially fatal condition known as Arrhythmia.

Until now, the genetic makeup of the CCS has been an enigma. But this week researchers led by the University of Utah published a study discussing a gene, called Tbx3, which they believe can interfere with the development of the CCS, causing lethal arrhythmias when it’s not functioning properly.

The researchers found that the CCS is extremely sensitive to levels of the Tbx3 protein. Alterations to the structure of the Tbx3 gene lead to varying levels of the Tbx3 protein. When levels fell too low, mice embryos developed arrhythmia – when they increased too much, embryos survived but adult mice faced sudden death from arrhythmia.

Anne M. Moon, M.D., Ph.D., adjunct professor of pediatrics at the U of U School of Medicine and corresponding author on the study, believes Tbx3 gene dysfunction could be a direct cause of arrhythmia.

What Moon doesn’t know is specifically how the Tbx3 protein regulates the behavior of cells in the CCS and whether cells that don't have enough of the protein die or turn into some other kind of cells.

In the grand scheme of things, identifying the Tbx3 gene structure that ensures optimal levels of Tbx3 protein in CCS cells, in turn leading to a healthy heart rhythm, could assist in the regeneration heart tissue.

"There's a big effort to regenerate heart muscle," 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."

The study is published in the December 26 issue of the journal Proceedings of the National Academy of Sciences.