Alpha 1-antitrypsin deficiency--diagnosis, treatment, and control: identification of patients.

Severe alpha 1-antitrypsin (AAT) deficiency is a relatively common inherited condition in populations of Northern European heritage. Current estimates of the prevalence of the PiZ phenotype range between 1/3500 and 1/1670 in the United States. Clues to the whereabouts of the undiagnosed individuals with severe hereditary AAT deficiency can come from the existing information about the natural history and clinical course of disease. In the PiZ smoker, dyspnea develops soon after age 30 years or at least before age 40, and death from emphysema is likely by age 50. The PiZ nonsmoker has a prognosis only marginally worse than that of the susceptible smoker without AAT deficiency. Dyspnea often does not appear until after age 50 years, and clinically significant emphysema not usually until after age 60. All infants presenting with liver disease in the neonatal period should be tested for the deficiency. In adults, clinically significant dyspnea in the 30s and 40s, in association with abnormal lung function, should raise the suspicion of AAT deficiency. In nonsmokers, dyspnea at any age justifies further investigation. A serum AAT level below 80 mg/dl (11 microM) is considered abnormal; individuals falling in this range should be phenotyped. The formation of a Registry for severe hereditary AAT deficiency in the United States, under the auspices of the National Heart, Lung and Blood Institute of the NIH, is also described.