Division of Cardiology

The Genetics of Sudden Death

Thomas V. McDonald, M.D.
Professor of Medicine (Cardiology)
Professor of Molecular Pharmacology
Albert Einstein College of Medicine
Attending Cardiologist, Department of Medicine
Montefiore Medical Center
Co-director, Montefiore Einstein Cardiogenetics Clinic

Potassium is a key heart-rhythm regulator: it creates the right environment for the electrical “spark” that triggers the heartbeat. In a cocaine user who died suddenly, Dr. McDonald and his colleagues discovered a genetic mutation (called KCNQ1-S277L) that disrupted the heart’s potassium balance and thus its ability to carry electrical current. In another sudden-death victim, an obese patient who had undergone stomach banding and was having trouble keeping liquids and solids down, they found a different genetic mutation (called G816V HERG). Both mutations caused a dangerous condition called Long QT Syndrome (LQTS), in which the heartbeat’s QT interval is delayed.

For people with LQTS, the first sign of trouble may be a fatal heart arrhythmia. But detecting the genetic defect early can alter that script. In both cases, Dr. McDonald’s team found the same mutations in some family members. The team prescribed medication and counseled these people on living with their disorder. The case studies were described in 2011 and 2012 issues of Pacing and Clinical Electrophysiology.

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