title: Serum levels of alpha1-antitrypsin predict phenotypic expression of the alpha1-antitrypsin gene.
abstract: We conducted a retrospective analysis to determine if both alpha1-antitrypsin serum level and phenotype need be studied when evaluating children for alpha1-AT deficiency. We collected data from patients less than 19 years old who had both serum alpha1-AT level and phenotype determined over a 9-year period (January 1992-December 2000). Eighty-eight patients were identified and 15 had the PiZZ phenotype. The serum alpha1-AT level was below normal (normal 85-215 mg/dl) in all 15 PiZZ patients. Seventy-two of 73 non-PiZZ patients had normal or above normal serum levels. The sensitivity of the serum alpha1-AT level was 100%, and the specificity was 99%. The serum alpha1-AT level had a positive predictive value of 94% and a negative predictive value of 100%. We conclude that serum alpha1-AT levels are highly predictive of the PiZZ phenotype. Determination of the serum alpha1-AT level alone should be the initial test when evaluating for alpha1-AT deficiency.
authors.affiliation: Division of Pediatric Gastroenterology/Hepatology/Nutrition, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana 46202-5225, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Steiner
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Croffie
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Fitzgerald
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D010641:Phenotype; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D000515:alpha 1-Antitrypsin / Q000032:analysis*; D019896:alpha 1-Antitrypsin Deficiency / Q000175:diagnosis* / Q000235:genetics*
chemical_list: D000515:alpha 1-Antitrypsin