Referenced in: none

Automatically associated channels: Kv11.1 , Kv7.1 , Nav1.5

Title: Postmortem molecular screening in unexplained sudden death.

Authors: Sumeet S Chugh, Olga Senashova, Allison Watts, Phuoc T Tran, Zhengfeng Zhou, Qiuming Gong, Jack L Titus, Susan J Hayflick

Journal, date & volume: J. Am. Coll. Cardiol., 2004 May 5 , 43, 1625-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/15120823

Abstract
We examined the prevalence of defects in arrhythmia-related candidate genes among patients with unexplained sudden cardiac death (SCD).Patients with unexplained sudden death may constitute up to 5% of overall SCD cases. For such patients, systematic postmortem genetic analysis of archived tissue, using a candidate gene approach, may identify etiologies of SCD.We performed analysis of KCNQ1 (KVLQT1), KCNH2 (HERG), SCN5A, KCNE1, and KCNE2 defects in a subgroup of 12 adult subjects with unexplained sudden death, derived from a 13-year, 270-patient autopsy series of SCD. Archived, paraffin-embedded myocardial tissue blocks obtained at the original postmortem examination were the source of deoxyribonucleic acid for genetic analysis.Two patients were found to have the same HERG defect, a missense mutation in exon 7 (nucleotide change G1681A, coding effect A561T). The mutation was heterozygous in Patient 1, but Patient 2 appeared to be homozygous for the defect. Patch-clamp recordings showed that the A561T mutant channel expressed in human embryonic kidney cells failed to generate HERG current. Western blot analysis implicated a trafficking defect in the protein, resulting in loss of post-translational processing from the immature to the mature form of HERG. No mutations were detected among the remaining four candidate genes.In this autopsy series, only 2 of 12 patients with unexplained sudden death were observed to have a defect in HERG among five candidate genes tested. It is likely that elucidation of SCD mechanisms in such patients will await the discovery of multiple, novel arrhythmia-causing gene defects.