Alpha-1-antitrypsin MZ phenotype and cryptogenic chronic liver disease in adults.

Intrahepatocytic inclusions of alpha-1-antitrypsin as markers of Z allele were searched by histochemical and immunohistochemical (peroxidase-antiperoxidase) methods in needle biopsy specimens from 80 consecutive cases of cryptogenic cirrhosis and chronic active hepatitis - HBsAg-negative - in adults. All positive cases and 26% of the negative ones were phenotyped in order to determine the frequency of heterozygous (MZ) deficiency. At variance with previous studies, no prevalence of heterozygous (MZ) deficiency could be demonstrated. This result indicates that further investigations are mandatory to establish if heterozygous (MZ) subjects are predisposed to chronic liver disease.