Health Desk: 16 April 2018: Scientists say they have identified genes that cause a deadly heart condition that can only be cured by transplants of the heart or lungs.
Pulmonary arterial hypertension kills 50% of those affected within five years, but little was known about what caused the condition in some people.
Now experts say they have discovered five genes that cause the illness.
The findings could lead to earlier detection of the disease and ultimately new treatments, researchers say.
Pulmonary arterial hypertension (PAH) currently affects around 6,500 people in the UK and causes the arteries carrying blood from the heart to their lungs to stiffen and thicken, ultimately leading to heart failure.
It is often diagnosed in people who have other heart or lung conditions, but it can affect people of any age and in about a fifth of people there is no obvious cause.
The only "cure" is a transplant of the heart and particularly the lungs, but there is a waiting list for organ transplants and the body will often ultimately reject them, particularly in the case of lungs.
For this latest research, published in Nature Communications, scientists carried out the largest ever genetic study of the disease by analyzing the genomes - the unique sequence of a person's DNA - of more than 1,000 PAH patients for whom the cause of the illness was unknown.
They found that mutations in five genes were responsible for causing the illness in these people, including in four genes that were not previously known to be involved in the disease.
In people with the condition these genes fail to effectively produce the proteins that are required for the structure, function and regulation of the body's tissues, researchers found.
Nick Morell, the lead author of the paper and professor at the British Heart Foundation, told BBC News: "Identifying the nature of these new genes and mutations in the new genes tells you what causes the disease.
"It allows you to design and come up with potential new ways of treating the disease because you have really well-grounded knowledge about what's actually causing it in cases where you find these mutations," he explained.