Caleb Hutchinson-Brown was born into an extended family scarred by inherited heart disease.
Caleb, of Tuakau, south of Auckland, is 13. It was last year that he was diagnosed with the heart rhythm disorder, long QT syndrome, named for electrical impulses in the heart. The condition can cause sudden death during exercise or stress, but also during sleep.
"When Caleb sleeps in in the mornings, I freak out a little bit," said his mother, Suzanne Brown, who has become familiar with the disease.
She said Caleb's biological father, her former partner, had suffered heart palpitations and dizziness, but there had been much worse in his extended family.
"The first really noticeable case was in 1976. It was Caleb's paternal grandmother's auntie. She was 26. She saw something that gave her a fright. It sent her into cardiac arrest and she died.
"She was a mother of three little kids.
"That got people wondering."
Then in 1996, Caleb's grandmother collapsed in the Papakura town centre from a cardiac arrest. She was technically dead for 14 minutes before being revived by an ambulance paramedic. She had had a pacemaker implanted after that.
"That's how we found out what was going on with the family history. Caleb's father was told he would have to have tests done. Having Caleb, we knew it was a 50/50 chance of him having it."
He was monitored as a child by electrical tests of his heart, which found only a small degree of abnormality.
Then last year he had a gene test for long QT syndrome. It came back positive.
"It takes three months to come back. While we were waiting his symptoms got worse," Mrs Brown said.
"Even as a little kid he would say to us to feel his chest because his heart was beating really quickly. As he got older he would get dizzy and tunnel vision."
The diagnosis led to Caleb having to take beta-blocker medication, which blocks the effects of adrenaline.
After he started taking the first beta blocker prescribed, Caleb suffered extreme fatigue, insomnia, very cold hands and feet and irritability, his mother said.
"The next check-up was two months ago. They changed his beta blocker and now he's getting back into sport because he's got more energy."
But he has to re-think his future.
"He wanted to be in the army or a police dog handler," said Mrs Brown. "He can't do those things now and that's a bit upsetting."
Finding genetic answers
When an apparently healthy young person dies suddenly and unexpectedly of a previously unknown heart problem, their family understandably becomes desperate for answers.
How could it have happened? Why were there no warning signs? Could any of the rest of us be affected too?
It is thought about 90 people aged 1 to 35 suffer sudden deaths in New Zealand each year from inherited heart diseases, such as the heart rhythm disorder long QT syndrome and hypertrophic cardiomyopathy.
"Deaths from this condition [long QT syndrome] are more common than deaths from cervical cancer yet it doesn't get in the newspapers," said paediatric heart specialist Dr Jon Skinner, of Starship children's hospital in Auckland.
Part of Dr Skinner's salary is paid by Cure Kids, the key financial backer of a long-term project to improve knowledge of cardiac inherited diseases - and to find people who don't know they have these conditions - through a national registry. The aim is to screen relatives of victims of sudden, unexplained deaths where inherited heart disease may be the cause.
Dr Skinner said the expected prevalence of long QT syndrome was about one person in every 2500.
"We've identified it in one in 4500 in the Auckland District Health Board area, so we are already half way there in terms of the numbers detected."
A Cure Kids research collaboration with the Auckland Medical Research Foundation is producing new insights into the genetic causes of long QT syndrome.
Slight variations in genes - single nucleotide polymorphisms or "Snips" - often did not matter, Dr Skinner said. "But if you happen to have, say, two of those Snips that modify gene function a little bit, if you put them together you might end up with a nasty disease when you've got the mutation."