Three weeks after his 50th birthday, my brother Blair came in from walking his labrador, sat down at the kitchen table and collapsed.
"If my girlfriend, Debbie, hadn't been with me, there's no question, I'd be dead," he says. "One minute I was fine, a bit breathless. The next, I felt myself keeling over, losing consciousness and there was nothing I could do. Debbie went into autopilot, put me in the recovery position and pumped so hard my chest was covered in bruises. She got my heart going again. She'd learned to resuscitate because her brother has epilepsy."
The natural assumption from both family and doctors, reinforced by a now erratic ECG, was that Blair had suffered a heart attack. Exactly like our 47-year-old, tennis-playing dad – a walk, something to eat, then a massive coronary – except Blair survived and Dad died.
So it was a mystery when, admitted to his local hospital, a blood test revealed it definitely wasn't a heart attack.
"I was in limbo. They couldn't let me go home or even off the ward for fear my heart would fail again and this time be fatal. All they could do was keep me on a heart monitor, feed me and give me beta blockers while we waited for an MRI at the specialist heart unit 15 miles away. Stuck on a general ward, watching my hospital, Tameside, slated on television as 'failing', I was stressed to hell. Thankfully, I was under a great young doctor, Mark Aitken, who eventually clicked what was wrong and helped with my transfer to the University Hospital of South Manchester."
It turned out Blair has a silent killer – hypertrophic cardiomyopathy (HCM) – the same condition that struck down the Cameroon footballer Marc-Vivien Foe on the pitch; and Rising Damp's Leonard Rossiter as he waited to go onstage. It's a genetic heart condition that causes thickening of the heart muscle and impedes effective pumping. Though it affects 1 in 500 people (more than much more visible diseases such as cystic fibrosis) many people don't know they've got it until it's too late.
"After my MRI, Dr Aitken drew me a picture of my heart. The muscle on both sides of the left ventricular chamber was so overgrown it was almost touching at points. I'm lucky my heart didn't fail sooner."
HCM breaks the pattern of most heart disease. It is the leading cause of heart-related sudden death in young people, excessive muscle tending to develop during puberty and early adulthood (sometimes also as a baby, as in the recent high-profile case of Lisa Yue in America, who lost two babies to it). Equally, it doesn't necessarily raise blood pressure, even at the critical stage like Blair's, because the heart can't pump strongly enough. And while the general population is told a good dose of sport protects the heart, anyone with the HCM gene is advised against strenuous exercise.
Once Blair was off the critical list, more shockwaves resonated through our family as the high probability that others had it too dawned. With a 50/50 chance of inheriting it, several deaths in the past began to make sense – my dad's; his swimmer mother's who was found dead on the beach in her costume with no water in her lungs; and her mother, who also died young, suddenly and inexplicably.
Unpleasant realities about the present surged: if HCM killed our ancestors (which we will never know for sure) and Blair has it, who else might? Siblings? Children? Cousins? Aunts, uncles? Overnight, every instance of a child fainting became potentially significant.
Blair's children, both in their early twenties, have a one in two chance of inheriting the condition. They're waiting for the results of his genetic tests to give them a clearer idea.
"I'm worried for them," Blair acknowledges. "I know they're feeling the strain. It's a big shock."
Dr Kay Metcalfe, Blair's consultant geneticist at St Mary's Hospital, Manchester, explains: "There's a 60 to 70 per cent chance of pinpointing the gene with the five genes we test. If we identify it, all first-degree relatives are offered tests, too."
She concedes that hospitals could look for additional genes, but genetic identification is costly and, once you move beyond the main genes, it produces ever-decreasing returns.
As anyone who's considered tests for other genetic conditions knows, identification brings with it myriad difficulties: the psychological shift, crossing that line from full fitness to potential incapacity; the practical – insurance, mortgages, even jobs; and the chance that you have the gene (and therefore the worry) but might never develop the disease. Or that you don't have active disease, but your children might. One reassurance is, HCM doesn't jump a generation: if you don't have the gene, your children won't.
Debate, controversy even, surrounds the gene testing: how many genes to test and whose, as well as screening more generally. The Italians check all athletes for HCM – and (though it is contested in other countries) claim it has significantly reduced deaths. Organisations such as Cardiac Risk in the Young (CRY) advise first-degree relatives to have yearly checks – ECGs and echocardiograms – until the age of 21; then every five years. A recent report in the specialist journal Cardiogenetics concludes that genetic testing is the most cost-effective option for immediate family.
Family members have reacted differently. Most have decided to wait the three months until the results of Blair's gene tests are back. Some would rather not know. One of my sons, a swimmer and water polo player, took himself straight off for an echocardiogram. Coincidentally, I was scheduled to have one. Neither revealed muscle thickening, for now.
After a six-week stay, Blair left hospital, patched up; not cured. His defibrillator (ICD) monitors and kick-starts his heart, but only risky open-heart surgery can cure him. He is not allowed to drive and the DVLA revoked his licences. As a cab driver with an HGV licence, too, he's lost his income. He understands why, but thinks all professional drivers, like athletes in Italy, should be screened: "Imagine the carnage if I'd been driving a heavy lorry down the M62."
Breakthroughs in treatment may not be far away. Professor William McKenna of University College London and president of the Cardiomyopathy Association explains: "Animal studies at Harvard show HCM can be delayed by introducing normal genes to inhibit the deleterious effects of disease-causing mutations. Medicines are also being developed that target the problems caused by specific gene mutations."
This is not the first journey Blair and I have taken together into family genetics. Last time it was to save my life, when, instead of the early heart attack I'd half-expected since adolescence, I was diagnosed with chronic myeloid leukaemia. The fact that our tissue types matched was a cause of celebration and great relief. Blair gave me his bone marrow for a transplant and has continued to donate cells for top-up treatments ever since.
Somehow it seems unjust that today we're all hoping the rest of our genes differ.
"What doctors don't know yet," Blair says "is whether my heart has been like this since I was a teenager, or whether it's got worse over the years. They will only have a chance of telling if someone younger is identified and they watch them. Let's hope that doesn't happen."