What is the role of the LQT2 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 LQT2 gene (HERG or KCNH2) encodes for part of IKr rapidly activating, rapidly deactivating, delayed rectifier potassium channel. [7, 8] Mutations in this gene cause rapid closure of the potassium channels and decrease the normal rise in IKr. They also result in delayed ventricular repolarization and QT prolongation. About 200 mutations in this gene have been detected.

Japanese researchers have identified two novel KCNH2 missense mutations, G785D and T826I, that disrupt the intracellular transport of KV11.1 to the plasma membrane; low-temperature incubation appears to restore plasma membrane expression of Kv11.1-T826I but not G785D. [9]

More than 30% of identified LQT2 mutations consist of nonsense or frameshift mutations that introduce premature termination codons (PTCs), which lead to the degradation of mutant mRNA by nonsense-mediated mRNA decay, an RNA surveillance mechanism that selectively eliminates the mRNA transcripts that contain PTCs. [8]


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