Medical view: The sudden death on Sunday of 29-year-old Michael Byrne while playing soccer, a little over a year after his younger brother also died playing for the same team, is a huge blow both to the family and the community in Ballykeefe, Co Kilkenny.
Both men are almost certainly victims of sudden cardiac death in the young.
Formally known as Sudden Adult Death Syndrome, the term now used for this condition is Sudden Arrhythmic Disease Syndrome (Sads). This is a reference to the fact that it is the acute onset of a chaotic rhythm in the heart that leads to the victim's sudden death.
While the first recorded case of Sads occurred during the marathon in ancient Greece, the condition has been brought to public attention following a number of high-profile deaths.
Cameroon soccer star Marc-Vivien Foe died suddenly during an international match against Colombia in June 2003. Tyrone GAA star Cormac McAnallen is another recent victim.
Speaking recently at a West of Ireland Cardiology Foundation lecture, a world expert in Sads, Prof Bill McKenna of University College London, outlined the latest understanding of the condition.
He told doctors that in those under 25, the common reasons for the development of an arrhythmia are the presence of different forms of heart muscle disease and anomalies in the structure of the blood vessels supplying the heart (the coronary arteries).
Older people may die because they have prematurely developed a blockage in their coronary arteries (coronary heart disease).
Regardless of the cause, a common feature is the sudden development of an abnormal rhythm in the heart. This chaotic beating of the heart means blood is no longer pumped into the brain and the heart, leading to sudden death.
The rapid application of an external electric shock may jolt the heart's electrical system back to a regular beat. For those at high risk of the condition, the treatment of choice is to place an implantable cardiac defibrillator in the chest. This device automatically corrects the rhythm disturbance as soon as it starts.
The main risk factors for Sads include a family history of unexplained sudden death in a relative under the age of 40.
Unexplained fainting in young people is also a reason for suspicion.
When Sads is suspected the person should be examined by a consultant cardiologist.
While the exact prevalence of Sads is unknown, Prof McKenna estimates there are approximately 1,000 cases a year in Britain.