Referenced in: none

Automatically associated channels: Kv7.1

Title: A KCNQ1 V205M missense mutation causes a high rate of long QT syndrome in a First Nations community of northern British Columbia: a community-based approach to understanding the impact.

Authors: Laura Arbour, Saman Rezazadeh, Jodene Eldstrom, Gwen Weget-Simms, Rosemarie Rupps, Zoe Dyer, Glen Tibbits, Eric Accili, Brett Casey, Andrew Kmetic, Shubhayan Sanatani, David Fedida

Journal, date & volume: Genet. Med., 2008 Jul , 10, 545-50

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/18580685

Abstract
Hereditary long QT syndrome is named for a prolonged QT interval reflecting predisposition to ventricular arrhythmias and sudden death. A high rate in a remote, northern Canadian First Nations community was brought to attention.Two severely affected index cases and 122 relatives were ascertained using community-based participatory research principles. Genetic sequencing of five known genes responsible for long QT syndrome was carried out on the index cases, leading to the identification of a novel missense mutation. Functional properties of the identified mutation were studied in transfected mouse ltk- cells using whole cell patch clamp techniques. Corrected QT interval measurements were obtained from participants and subsequent genotyping of relatives was carried out.In the two index cases, a novel missense mutation (V205M) was identified in the S3 transmembrane helix of KvLQT1, the pore forming domain of the IKs channel complex. In transfected mouse ltk-cells the V205M mutation suppressed IKs by causing a dramatic depolarizing shift in activation voltage coupled with acceleration of channel deactivation. Twenty-two mutation carriers had a significantly higher mean corrected QT interval than noncarriers (465 +/- 28 milliseconds vs. 434 +/- 26 milliseconds, P < 0.0001); however, 30% of carriers had a corrected QT interval below 440 milliseconds.A novel KCNQ1 mutation in this founder population likely confers increased susceptibility to arrhythmias because of decreased IKs current. Even with a common mutation within a relatively homogenous population, clinical expression remains variable, exemplifying the multifactorial nature of long QT syndrome, and supporting the difficulty of definitive diagnosis without genetic testing. A community participatory approach enabled a comprehensive evaluation of the impact.