| What Is A1AD? - Page 2 |
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Scientists developed a way of showing these differences by using a gel plate to document the way the different varieties moved when subjected to an electric charge. They gave different letters to the different types of Proteinase Inhibitor they found, the Pi system. It was found that the least effective and most malformed AAT was the Z type. So, when a person is tested for A1AD the lab performs what is called a "Phenotype", which shows what sort of AAT the patient has. If you have two normal genes then the patient is described as PiMM, where the two "M's" mean that both genes for A1AD are normal and are producing normal AAT. In the highly deficient patient the results are likely to be PiZZ, showing that both genes for AAT are producing the near useless Z type. Without the protection of AAT the lung tissue can become slowly damaged by repeated infections and the unopposed neutrophil elastase that the white cells have released. Smoking causes these white cells to rush to the lungs so that anyone who is highly deficient, PiZZ, will be at a huge risk of developing severe, progressive emphysema at an early age. In Northern Europe the commonest type of deficiency is PiZZ, the worst sort. In Denmark, a country with a small, very inbred population the chance of having full-blown A1AD is 1:1600, which in Denmark makes it twice as common as Cystic Fibrosis. It is not know what the frequency is in the UK as no assays have been carried out but it's thought to be around 1:5000. Another quite common variety of the gene is given the label "S" type. This particular variety (allele) seems more common in Spain and Italy and is also found in Latin American Countries. So, we have seen that people with A1AD cannot produce enough of the protective protein, AAT and are at a high risk of developing severe emphysema, often in their forties. This is by far the most common disease caused by the deficiency.
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