DONEGAL brothers Edwin and Ronnie McCausland both inherited genes that leave them at an extra risk of lung disease.
But while Edwin now has chronic obstructive pulmonary disease (COPD) and cannot walk for long without an oxygen tank, Ronnie has no such health problems.
The difference is that Edwin was a smoker and Ronnie was not. They are living proof of research showing a genetic link with lung disease.
Edwin (68), from outside Lifford, had to give up work as an electrician after he was diagnosed in 2007.
"I smoked around 20 cigarettes a day but gave them up when I was told I had the disease.
"I first developed symptoms in 1991-1992 when I noted I was becoming short of breath when walking down the street. My breathing was aggravated by car fumes.
"My brother Ronnie is five years older than me and never smoked and he has no lung problems."
They both took part in the Alpha One Foundation study.
Edwin is currently attending the lung transplant unit of the Mater Hospital in Dublin and hopes to be lucky enough to undergo the operation in the future.