Referenced in: none

Automatically associated channels: Kv11.1 , Kv7.1

Title: Genotype-phenotype aspects of type 2 long QT syndrome.

Authors: Wataru Shimizu, Arthur J Moss, Arthur A M Wilde, Jeffrey A Towbin, Michael J Ackerman, Craig T January, David J Tester, Wojciech Zareba, Jennifer L Robinson, Ming Qi, G Michael Vincent, Elizabeth S Kaufman, Nynke Hofman, Takashi Noda, Shiro Kamakura, Yoshihiro Miyamoto, Samit Shah, Vinit Amin, Ilan Goldenberg, Mark L Andrews, Scott McNitt

Journal, date & volume: J. Am. Coll. Cardiol., 2009 Nov 24 , 54, 2052-62

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19926013

Abstract
The purpose of this study was to investigate the effect of location, coding type, and topology of KCNH2(hERG) mutations on clinical phenotype in type 2 long QT syndrome (LQTS).Previous studies were limited by population size in their ability to examine phenotypic effect of location, type, and topology.Study subjects included 858 type 2 LQTS patients with 162 different KCNH2 mutations in 213 proband-identified families. The Cox proportional-hazards survivorship model was used to evaluate independent contributions of clinical and genetic factors to the first cardiac events.For patients with missense mutations, the transmembrane pore (S5-loop-S6) and N-terminus regions were a significantly greater risk than the C-terminus region (hazard ratio [HR]: 2.87 and 1.86, respectively), but the transmembrane nonpore (S1-S4) region was not (HR: 1.19). Additionally, the transmembrane pore region was significantly riskier than the N-terminus or transmembrane nonpore regions (HR: 1.54 and 2.42, respectively). However, for nonmissense mutations, these other regions were no longer riskier than the C-terminus (HR: 1.13, 0.77, and 0.46, respectively). Likewise, subjects with nonmissense mutations were at significantly higher risk than were subjects with missense mutations in the C-terminus region (HR: 2.00), but that was not the case in other regions. This mutation location-type interaction was significant (p = 0.008). A significantly higher risk was found in subjects with mutations located in alpha-helical domains than in subjects with mutations in beta-sheet domains or other locations (HR: 1.74 and 1.33, respectively). Time-dependent beta-blocker use was associated with a significant 63% reduction in the risk of first cardiac events (p < 0.001).The KCNH2 missense mutations located in the transmembrane S5-loop-S6 region are associated with the greatest risk.