People with familial emphysema have a hereditary deficiency of alpha-1-protease inhibitor, also called alpha1-antitrypsin (AAT). When there is a genetic deficiency of AAT, the activity of elastasean enzyme that breaks down elastin - is not inhibited and elastin degradation occurs unchecked. Individuals with a severe genetic deficiency of AAT usually have symptoms of COPD by the time they reach early middle age. It is critical that people with this deficiency never smoke.
Destruction of alveolar walls, capillaries, and attachments between alveoli and bronchioles causes
- susceptibility of airways to compression and collapse, impeding airflow out of the lungs
- entrapment of air in the alveoli
- poor air-gas exchange, that is, reduced ability to inhale oxygen and exhale carbon dioxide (CO2), resulting in increased levels of CO2 in the blood
- the development of bullae (areas of lung extensively destroyed so that they become large dilated air sacs) and
- enlarged lungs.