Who is affected by A1AD?

A1AD genes are passed from parents to children. Everyone has two copies of the AAT gene. Most people have two normal copies.  If you have a normal gene and one abnormal gene, there may be some deficiency, but A1AD sufferers usually have two disease-associated copies of that gene.

The genes are the coded plans for the cell to make AAT, so if the genes are faulty, the amount of AAT made is low or faulty.  The severity of any problem depends on how much AAT is made and released into the bloodstream. The less that is present in the blood, the more trouble results.  AAT levels in the bloodstream may range between 10-80% of normal levels. For emphysema to result, the level is usually well down. In NZ, the laboratory normal range is quoted as 1.2-2.0 gm/litre. Problems are not usually seen until levels are under 0.8, and more usually as low as 0.5. Levels of 0.3 or less are often seen in individuals with severe A1AD. The levels depend on the kind of abnormal gene the individual has.

Remember, though, that not everyone even with low levels of AAT will get emphysema, as the additional factor of airway inflammation (from smoke or dust or other conditions) is needed to cause damage.