Familial Emphysema / Alpha-1-Antitrypsin
People with familial emphysema have a hereditary deficiency of a blood component called alpha-1-antitrypsin resulting in the loss of a lung structural protein, elastin.
In the general population, emphysema usually develops in older individuals with a long smoking history. However, there is also a form of emphysema that runs in families.
People with familial emphysema have a hereditary deficiency of a blood component, alpha-l-protease inhibitor, also called alpha-l-antitrypsin (AAT). The number of Americans with this genetic deficiency is quite small, probably no more than 70,000. It is estimated that 1 in 3,000 newborns have a genetic deficiency of AAT, and 1 to 3 percent of all cases of emphysema are due to AAT deficiency.
The destruction of elastin that occurs in emphysema is believed to result from an imbalance between two proteins in the lung -- an enzyme called elastase, which breaks down elastin, and AAT, which inhibits elastase.
In the normal individual, there is enough AAT to protect elastin so that abnormal elastin destruction does not occur. However, when there is a genetic deficiency of AAT, the activity of the elastase is not inhibited and elastin degradation occurs unchecked.
If individuals with a severe genetic
deficiency of alpha-l-protease inhibitor smoke, they usually have symptoms
of COPD by the time they reach early middle age. Deficiency of
alpha-l-protease inhibitor can be detected by blood tests available
through hospital laboratories. People from families in which relatives
have developed emphysema in their 30s and 40s should be tested for AAT
deficiency. If a deficiency is found, it is critical for these people not
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