More often than not someone is diagnosed with A1AD because they have become ill. In the case of lung disease this often happens so slowly that the patient doesn't actually get a diagnosis until around half of lung function has been lost.

A mis-diagnosis of "adult onset asthma" is very common. The early symptoms of cough, wheeze and a tendency to develop chest infections are difficult to separate from asthma. Of course once a diagnosis has been made other affected family members may be identified by screening. This might not be the right course of action to take in every situation.

It remains unclear what insurance companies might do in then future regarding genetic conditions. At the moment the banning of companies asking for test results has just been extended. If you are in this situation it would be best to take advice, possibly from the NHS genetic counselling service.

What is undoubtedly true is that knowing you have "full-blown" A1AD is very important. It enables individuals to make certain life choices that will help prevent the development of disease, and may slow down progression if disease is present.

Rather obviously, the most important choice to make is not to smoke. Other considerations are working environment and the prompt, aggressive treatment of any chest infections.

When Erikkson first described A1AD in the mid sixties he estimated that 80% of people with the PiZZ phenotype would develop emphysema and probably die in their fifties. Officially the average age of death is still put at 54, but this is quite clearly in need of updating. Speaking at a conference in 1999 he had now decided that for lifetime non-smokers it was likely that only around 20% would develop significant emphysema at an early age.

What seems absolutely clear is that even smoking moderately for a few years is enough to start the disease process and, once started it will always progress. However the rate of that progression is enormously variable. Some people are needing a lung transplant in their late twenties others are only slightly "wheezy" in their seventies.