Dr. Michael Gollob, Cardiologist, and Clinical Scientist, discusses a novel gene discovery in a family with atrial fibrillation – the most common type of irregular heart rhythm.
(Video: PMCC/UHN)

Clinical researchers at the Peter Munk Cardiac Centre (PMCC) have discovered a gene that may help unravel the mystery surrounding the most common form of heart rhythm disorder – atrial fibrillation – specifically when inherited by family members.

"Atrial fibrillation is very common," says Dr. Michael Gollob, cardiologist and clinical electrophysiologist at PMCC, who led the study. "It is a very challenging arrhythmia to control, both with medical therapy and cardiac procedures.

"Many patients become refractory to medical therapy or become intolerable to side-effects."

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The study, entitled "A mutation in the atrial-specific myosin light chain gene (MYL4) causes familial atrial fibrillation," appears in the April 2016 edition of Nature Communications.

The study focused on examining the genes of five members of the same family, all of whom are from Canada and each of whom had atrial fibrillation, a chronic condition.

"We analyzed their genes using cutting-edge genomic technology," says Dr. Gollob, who was recruited by PMCC in 2014 and is a leading international expert on the electrical malfunctions of the heart and abnormal heartbeats. "We performed whole exome sequencing on the DNA of affected individuals and compared that to other members of the family who did not have the disease and looked at the DNA profiles of both the affected and unaffected individuals."

Dr. Gollob is also the Chair of the Peter Munk Centre of Excellence in Molecular Medicine.

"Using this type of genetic study, we were able to identify some rare genetic variants that affected members in the family carried, that unaffected members did not carry," Dr. Gollob says. "One of these genetic findings was a novel genetic mutation in a gene that is highly expressed it he atrial chambers of the heart.

"And this particular gene encodes a protein that is involved in the structure of the atrial myocardium. And this was a novel mutation that all affected members of the family had."

"This type of study is what drives us to perform gene discovery research," Dr. Gollob says. "These findings together with the genetic observations were rather conclusive in suggesting that we had identified a novel gene, in a Canadian family, responsible for atrial fibrillation."​

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