Irish researchers have made a major breakthrough in understanding why women with the life-threatening disease cystic fibrosis (CF) have a poorer survival rate than men.
Academics found higher levels of the hormone oestrogen limits the lungs' ability to fight infection and bacteria that attack good cells.
CF is a life-threatening inherited disease which targets the lungs and the digestive system.
A build-up of mucus can make it difficult to clear bacteria and leads to cycles of lung infections and inflammation, which can eventually damage a patient's lungs.
Ireland has both the highest incidence of CF in the world - at 2.98 per 10,000 - and the highest carrier rate in the world with one in 19 individuals classed as carriers.
The incidence of cystic fibrosis in Ireland is almost four times the average rate in other EU countries and the USA.
Researchers from the Royal College of Surgeons in Ireland (RCSI) and Dublin's Beaumont Hospital studied why female CF patients have poorer survival rates, poorer lung function and are more susceptible to lung infections than male CF patients.
They found oestrogen limits the lungs' ability to respond to infection and revealed it prevented the release of a chemical signal (IL-8) that triggers the influx of white blood cells (neutrophils) into the lungs to fight the infection when cells are attacked by bacteria.
The study was published in the American Journal of Respiratory and Critical Care Medicine.
Dr Sanjay Chotirmall, joint lead author of the paper, said: "Our ultimate aim would be improving the quality of life and survival rate for female sufferers of cystic fibrosis."