Genetic Explanation for Some Unexplained Cardiac Deaths

NOVEMBER 12, 2016
Gale Scott
Researchers have found genetic clues to the riddle of why some people die of sudden unexplained cardiac incidents even when their hearts look normal.

In six cases of idiopathic bundle branch reentrant ventricular tachycardia, researchers found three patients with culprit mutations. Those were two with SCN5A (Ala 1905Gly and c.4719>T, and one in LMNA (Leu327Val.)

Biolphysical analysis showed mutant Ala1905Gly sodium channels in tsA201 cells had "significantly reduced peak current density" and positive shifts in the voltage-dependence of activation. 

That likely explains loss of function, Jason Roberts, MD, MAS of Western University, London, Ontario, Canada and colleagues there and at other institutions reported at the American Heart Association Scientific Sessions 2016 in New Orleans, LA. 

Their findings were simultaneoulsy published in the Journal of the American College of Cardiology: Clinical Electrophysiology

The investigation is the first time genetic culprits for this life-threatening arrhythmia have been found. 

It could also explain a new genetic reasons behind sudden cardiac death in apparently healthy people, including young people. 

Fortunately, the team also found, the condition can be cured with catheter ablation. 

The patients were all younger than 60 and were recruited for six North American medical centers. All had tachycardia and normal biventricular size and function. 

All got genetic testing. 

The mean age at diagnosis was 26 year and four were male. 

One implication of the study is that genetic testing can be useful in diagnosing the cause of some arrhythmias.

A larger study will be needed to determine how common the mutations might be in this group of patients, the authors noted.

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