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Deficiencies in the serum protease inhibitor alpha1-antitrypsin (AAT) result from AAT gene mutations. Heterozygous (PiMZ) and homozygous (PiZZ) individuals have moderate and severe deficiencies, respectively. The mutant Z allele encodes a structural change in the glycoprotein (lysine in place of glutamic acid at position 342), resulting in abnormal folding and retention in the endoplasmic reticulum, leading to accumulation of eosinophilic, PASD+ globules in hepatocytes. The globules are 1-10 microns and are predominantly in periportal hepatocytes. This may progress to chronic hepatitis, cirrhosis (shown here), or hepatocellular carcinoma.