One in 25 Irish people have an increased risk of developing the serious lung disease, COPD, due to a combination of inherited genes and exposure to cigarette smoke, scientists have discovered.

COPD (chronic obstructive pulmonary disease) is an umbrella term for a number of chronic lung disorders, including bronchitis and emphysema. It is a progressive, disabling condition caused by a narrowing of the airways. Smoking is the main cause.

The disease currently affects around 440,000 people in Ireland and it is the world's fourth biggest killer.

Now scientists from the Alpha One Foundation, the Royal College of Surgeons in Ireland and Harvard University in the US have identified a significant proportion of the Irish population who have an increased risk of developing this condition.

The research relates to Alpha-1 antitrypsin, a protein that protects the lungs. If a person is deficient in this protein, they develop a condition known as Alpha-1. This is the most common fatal inherited lung condition in Ireland after cystic fibrosis.

Prior to this latest study, the increased risk of developing COPD as a result of Alpha-1 was thought to only affect people who inherited two abnormal (ZZ) Alpha-1 genes.

However, the scientists have proven that an estimated one in 25 people in Ireland, who has inherited a combination of one normal (M) and one abnormal (Z) Alpha-1 antitrypsin gene, is at an increased risk of developing COPD.

Exposure to cigarette smoke is the biggest risk factor in determining if those who carry this MZ combination of genes are at an increased risk of COPD, compared to those who have two normal (MM) Alpha-1 genes.

As such a large number of people in Ireland have this MZ combination of genes, the scientists believe that it is essential that anyone diagnosed with COPD be tested for Alpha-1.

Of the estimated 250,000 people in Ireland with the MZ combination, around 1,500 have so far been identified.

"This research signals a major breakthrough in understanding the heightened risk of COPD for people who have the combination of one normal and one abnormal Alpha-1 antitrypsin gene. If people know that they have a genetic predisposition to developing COPD, it allows intervention at an earlier age, encourages smoking cessation and prevents a further decline in lung function in a disease that is otherwise preventable.

"It also provides an opportunity for other family members to get tested for Alpha-1," said principal investigator, Prof Gerry McElvaney of the RCSI.

Prof McElvaney is also chairman of the Alpha One Foundation, which provides free national screening for Alpha-1 in Ireland. This is the only national screening programme for Alpha-1 in the world.

"We strongly urge people to avail of this service, particularly if they have COPD. Also as Alpha-1 is a hereditary disease, we recommend that all first degree family members of individuals with Alpha-1 should be tested. It can be easily diagnosed by a simple blood test," he noted.

According to the study's lead author, Dr Kevin Molloy of the RCSI, Alpha-1 continues to be ‘massively under-diagnosed both in Ireland and internationally'.

"As this research has an impact on a large number of people who have the MZ gene combination, it will greatly increase awareness and diagnosis of Alpha-1. Knowing that you have a genetic predisposition to developing COPD should encourage people to avoid exposure to cigarette smoke if they definitively know they have a higher risk of developing this debilitating lung condition," he noted.

Some 250 people from 51 families took part in the research. Details of the study findings are published in the American Journal of Respiratory and Critical Care Medicine.

For more information on how to be tested for Alpha-1, contact the National Centre for Alpha-1 based at Beaumont Hospital, Dublin, on (01) 809 3871 or email alpha1@rcsi.ie