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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Characterization of a novel missense mutation in the pore of HERG in a patient with long QT syndrome.

INTRODUCTION: A new strategy to elucidate the molecular mechanisms underlying the long QT syndrome (LQTS) is now available with genetic mutational analyses and characterization of ion channel mutations. METHODS AND RESULTS: In a 26-year-old woman with LQTS, we identified a novel missense mutation in the pore of HERG by using polymerase chain reaction/single-strand conformation polymorphism (PCR/SSCP) and sequencing of her genomic DNA. The mutation resulted in an amino acid substitution of a positively charged lysine for a highly conserved uncharged asparagine at codon 629 (N629K). Whole cell, patch clamp studies were conducted in COS7 cells by transfecting with wild-type (WT) and/or the mutant N629K HERG. The WT HERG produced an I(Kr)-like, E-4031-sensitive conductance with an inward rectification. In contrast, the cells transfected with the N629K HERG did not display any time-dependent current. Cotransfection of WT and N629K HERG (at a ratio of 1:1) produced a significantly smaller conductance when compared with WT HERG (WT 59.9 +/- 7.3 pA/pF [n = 22] vs WT+N629K 5.5 +/- 2.3 pA/pF [n = 11]; P < 0.01), but did not alter K+ ion selectivity and tail current-voltage dependence. Because aprindine hydrochloride was effective in preventing ventricular tachycardias, we also tested the effect of the drug on WT HERG (I(Kr)) and KvLQT1/KCNE1 (I(Ks)) currents expressed in COS7. CONCLUSION: Functional analyses of a novel missense mutation in the pore of HERG suggest that the mutation causes marked reduction of I(Kr) via a dominant negative effect.[1]

References

  1. Characterization of a novel missense mutation in the pore of HERG in a patient with long QT syndrome. Yoshida, H., Horie, M., Otani, H., Takano, M., Tsuji, K., Kubota, T., Fukunami, M., Sasayama, S. J. Cardiovasc. Electrophysiol. (1999) [Pubmed]
 
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