Ans. D: Alphal Anti-trypsinStage 4: Panac nar/Panlobular type of emphysema is associated with alphal-ant trypsin deficiencyEmphysemaIt is more commonly classified by location into panacinary and centroacinary (or panacinar and centriacinar, or centrilobular and panlobular.Panacinar (or panlobular) emphysema:- The entire respiratory acinus, from respiratory bronchiole to alveoli, is expanded.- Occurs more commonly in the lower lobes, especially basal segments, and anterior margins of the lungs. Centriacinar (or centrilobular) emphysema:- The respiratory bronchiole (proximal and central pa of the acinus) is expanded.- The distal acinus or alveoli are unchanged.- Occurs more commonly in the upper lobes.Other types include distal acinar and irregular.A special type is congenital lobar emphysema (CLE).The majority of all emphysema cases are caused by smoking tobacco.Severe cases of A1AD may also develop cirrhosis of the liver, where the accumulated A1AT leads to a fibrotic reaction.Patients with alpha 1-antitrypsin deficiency (A1AD) are more likely to suffer from emphysema.A1AT inhibits inflammatory enzymes (such as elastase) from destroying the alveolar tissue.Most A1AD patients do not develop clinically significant emphysema, but smoking and severely decreased A1AT levels (10-15%) can cause emphysema at a young age.The type of emphysema caused by A1AD is known as panacinar emphysema (involving the entire acinus) as opposed to centrilobular emphysema, which is caused by smoking.Panacinar emphysema typically affects the lower lungs, while centrilobular emphysema affects the upper lungs.A1AD causes about 2% of all emphysema.Smokers with A1AD are at the greatest risk for emphysema.Mild emphysema can often develop into a severe case over a sho period of time (1-2 weeks).