Genetic Basis Found for a Type of Arrhythmia

Researchers have found that a type of cardiac arrhythmia is due to the abnormal coordination of multiple functionally related ion channels and transporters, caused by a mutation in the gene for the protein ankyrin-B. Their findings were published in the February 6, 2003, issue of Nature.

By studying a French family with the Type 4 form of inherited Long QT Syndrome (LQTS) and performing experiments in mice, investigators from Duke University (Durham, NC, USA) located a mutation in the gene encoding ankyrin-B, a protein found within heart muscle cells.

Comparison of findings from humans with LQTS with those from mice with the E1425G mutation of ankyrin-B showed striking similarities in cardiac performance, including reduced heart rate, a high degree of heart rate variability, and other heart rate disturbances that could not be linked to electrolyte or structural defects of the hearts.

"We found that two normal copies of the ankyrin-B gene are necessary for normal calcium signaling, and that the E1425G mutation leads to a loss of function, explained first author Dr. Peter Mohler, post-doctoral fellow at Duke University. "So, ankyrin-B is the first identified protein implicated in a congenital LQTS that is not an ion channel.”



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