The mutation that causes A1AD is a single pair of transposed bases on the long arm of chromosome 14.

Geneticists believe that this has only occurred once, in a Scandinavian culture probably some 14,000 years ago.  The tiny population of this time would have more than likely had no taboos regarding incest and interbreeding.  It is by far the commonest recessive disorder in Scandinavia and is even called  'The Viking Disease'  in Denmark.

It has been suggested that around 2% of western populations have COPD.   In Denmark, where A1AD is most prevalent ( 1:1600) it is estimated that 2% of the COPD will be caused by A1AD and another 2% by partially deficient heterozygotes with a single Z allele.

The researchers suggest that if we say a PiMM's chance of developing COPD is 1 then PiMZ's have a chance of 1.5.

This might appear high but, given the very small chance of developing COPD in the general population, and the large numbers of PiMZ's, the risk to any individual MZ is very small.

In contrast PiZZ's have a risk factor of 12, using the same scale!

Of course, some 90% of COPD is the result of smoking, and that probably includes most with the deficiency.

Researched & quoted by a DX'd Alpha in the UK, Robin Muskett