Sudden Death in the Young and in Athletes Linked to Gene Mutation

A research team comprising of scientists from South Africa, Canada and Italy have discovered that a new gene can result in sudden death of athletes and young people by causing arrhythmogenic right ventricle cardiomyopathy (ARVC). This heart condition is caused by the gene CDH2, increasing the risk for a cardiac arrest, leading to unexpected death in young people. The study, which was published in the journal Circulation: Cardiovascular Genetics is an international collaboration that started 15 years ago. The research team led by Dr. Bongani Mayosi, a cardiology professor from the University of Cape Town and Groote Schuur Hospital, included scientists from the University of Pavia and the Italian Auxologico Institute of Milan. The genetic sequencing to identify the specific genetic variant was performed by Dr. Guillaume Paré and colleagues from the Population Health Research Institute of McMaster University and Hamilton Health Sciences.

Sudden Cardiac Death

Dr. Paré said that this study would help families get over their grief and will help families come to terms with what happened to their family member. The associate professor of pathology and molecular medicine with the Michael G. DeGroote School of Medicine said that finding out that there was a genetic cause will help families understand why their loved one died so suddenly.

The scientists further stated that his entire team was very happy to have contributed to the finding that a genetic mutation in the gene CDH2 was the culprit behind the death among a certain portion of the patients. Early identification of the presence of this gene variant can be used for preventative interventions as well as for genetic counseling.

According to the Heart and Stroke Foundation of Canada

• 40,000 cardiac arrests occur in Canada every year
• One in 10 people survive a cardiac arrest when it occurs out of the hospital

Cardiomyopathy

Cardiomyopathy caused due to an inherited genetic disorder under the age of 35, can lead to sudden cardiac arrest, and in turn to the death of the individual. In this inherited condition, the heart tissue is replaced by fibrous and fatty tissue. This leads to the development of cardiac arrhythmias like tachycardia and ventricular fibrillation, which can lead to the loss of consciousness and result in a cardiac arrest. Without a ready electrical defibrillation, ventricular defibrillation can cause death within a few minutes.

To understand the implication of this genetic mutation, Dr. Mayosi followed a South African family who were affected by arrhythmogenic right ventricle cardiomyopathy (ARVC) for a period of 20 years. This family lost several juveniles as a result of sudden death. The scientists screened all the genes to identify the gene variations that led to the development of this condition. The identification of the gene responsible was possible when the studies were conducted on 2 ill patients in the family, narrowing down to the gene CDH2, from over 13,000 common genetic variants.

CDH2 Gene

This gene, CDH2, is associated with the production of cadherin 2 or N-Cadherin, a vital protein that is necessary for normal adhesion between the cardiac cells. When the scientists screened for mutation in the genes of another family affected with the same condition, they found a mutation in another part of the same gene, highlighting the importance of this gene in arrhythmogenic right ventricle cardiomyopathy. Earlier studies conducted on genetically modified mice showed that the absence of the protein resulted in malignant ventricular arrhythmias, which lead to sudden death.

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The scientists state that associating the condition to the gene was very important as it served to understand the mechanisms that triggered arrhythmogenic right ventricle cardiomyopathy. This understanding can be used for early detection of this condition, which has thus far been a silent condition.

The Importance of CDH2 Gene on Heart Health

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In a study conducted by Dr. Igor Kostetskii and colleagues titled “Induced Deletion of the N-Cadherin Gene in the Heart” and published in the journal Circulation Research (2005), the importance of the gene CDH2 in heart health was determined.

The intercalated disc in the heart that contains junctional complexes like the zonula adherens, desmosomes and gap junctions maintains the structural integrity of the heart. These complexes need to be arranged appropriately in the disc for proper electrical signal conduction and for normal mechanical functions of the cardiomyocytes. In cardiovascular disease, these components are disturbed, though it is not known if these are associated with the development of the disease. The study highlighted that the maintenance of this cell junction was associated with the plakoglobin gene which is known to lead to arrhythmogenic right ventricular cardiomyopathy among humans. Plakoglobin, belongs to the armadillo protein family and is a protein present in the desmosomal and adherens junctions. Plakoglobin is also known as catenin. In the study, a mutation was induced in the CDH2 gene in mice, and it was found that there was

• Disassembly of the intercalated disc
• Modest dilated cardiomyopathy
• Impaired cardiac function
• The mice died within 2 months

The current study that identified the mutation, which lead to arrhythmogenic right ventricular cardiomyopathy among humans can be used for screening not only to aid the patient, but also to screen other members of a family where an individual has the genetic mutation in the CDH2 gene. This will aid in identifying the risk in the family, allowing the use of preventive strategies which could lower the risk of death. This condition has been a silent threat with sudden cardiac arrest leading, to the loss of life. However, screening for the gene mutation would help identify the condition before it is too late.

References:

1. Gene Found To Cause Sudden Death In Young People - (https://www.eurekalert.org/pub_releases/2017-03/mu-gft030917.php)

Source-Medindia