Final answer:
The most common cause of death in alpha1-antitrypsin deficiency is emphysema, a lung condition resulting from uncontrolled neutrophil elastase activity due to the lack of AAT, which also can lead to pediatric liver diseases.
Step-by-step explanation:
The most common cause of death in alpha1-antitrypsin deficiency is related to lung diseases, particularly emphysema. Alpha1-antitrypsin (AAT) is a protein that protects the lungs from neutrophil elastase, which can destroy the elastin in the alveolar walls. In individuals with AAT deficiency, uncontrolled elastase activity leads to the breakdown of elastin, causing emphysema and significantly impairing lung function. This lung deterioration can lead to life-threatening respiratory complications. Additionally, AAT deficiency can lead to pediatric liver diseases, with liver-related complications potentially contributing to mortality as well.