What is the role of the LQT4 gene in the etiology of long QT syndrome (LQTS)?

Updated: Nov 29, 2017
  • Author: Ali A Sovari, MD, FACP, FACC; Chief Editor: Mikhael F El-Chami, MD  more...
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Answer

The LQT4 gene (ANK2 or ANKB) encodes for ankyrin-B. Ankyrins are adapter proteins that bind to several ion channel proteins, such as the anion exchanger (chloride-bicarbonate exchanger), sodium-potassium adenosine triphosphatase (ATPase), the voltage-sensitive sodium channel (INa), the sodium-calcium exchanger (NCX, or INa-Ca), and calcium-release channels (including those mediated by the receptors for inositol triphosphate [IP3] or ryanodine).

Mutations in this gene interfere with several of these ion channels. The end result is increased intracellular concentration of calcium and, sometimes, fatal arrhythmia. Five mutations of this gene are reported. LQT4 is interesting, because it provides an example of how mutations in proteins other than ion channels can be involved in the pathogenesis of LQTS.


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