Researchers at the University of Cape Town (UCT), through global collaboration, have made a breakthrough in what has been hailed as the biggest breakthrough in South African cardiology since Dr Chris Barnard’s first heart transplant.
The researchers have identified a new gene called CDH2 that is a major cause of sudden death among young people and athletes.
CDH2 causes arrhythmogenic right ventricle cardiomyopathy (ARVC), which is a genetic disorder that predisposes patients to cardiac arrest and is a major cause of unexpected death in seemingly healthy young people.
The discovery, published in Circulation: Cardiovascular Genetics, is the result of an international collaboration that began 15 years ago and was led by a South African team headed by Bongani Mayosi, a Professor of Cardiology and Health Facility Dean at UCT and researchers from the Italian Auxologico Institute of Milan and the University of Pavia.
“The discovery of a gene is almost like looking for a needle in a haystack. Where you’ve got three billion changes in our genome, that’s what we have, and there’s this one spelling error that you are looking for in three billion letters, so it requires major detective work and that requires skill and technology from all over the world,” said Professor Mayosi.
Sudden cardiac death is estimated to affect more than five young people in South Africa every day‚ according to the Medical Research Council, while in Italy about 50,000 people die suddenly every year.
In ARVC, the heart tissue is replaced by fatty and fibrous tissue. This process encourages the development of cardiac arrhythmias such as tachycardia and ventricular fibrillation, which cause loss of consciousness and cardiac arrest. In the case of ventricular fibrillation, without a ready electrical defibrillation, it causes sudden death in a few minutes.
Professor Mayosi followed a South African family affected by ARVC that had experienced several cases of juvenile sudden death for 20 years. Excluding all genetic causes known at the time, the Italian researchers sequenced all the coding regions of the genome in two ill members of the family. The genetic mutation responsible for the disease in the family, CDH2, was narrowed down from more than 13,000 common genetic variants present in the two ill patients.
“This is important news for families who have had a young family member suffer a sudden cardiac death, for them to know a genetic cause has been identified,” said Dr Guillaume Paré, who led the team that performed the genetic sequencing, as well as the bioinformatics analysis for the study.
“Our team was happy to contribute to the finding that a mutation in CDH2 is the underlying culprit in a portion of these patients. This will pave the way for preventative interventions and genetic counselling,” concluded Dr Paré.
The researchers said identifying the gene is important because it helps to clarify the genetic mechanisms underlying ARVC, and it also makes the early detection of ARVC possible in otherwise unsuspecting people.