Realities of observational study registration.

The patient’s serum -1 globulins were reduced at 1.3 g/L (reference interval, 2.1–3.5 g/L). Potential causes include malnutrition, excessive excretion, decreased production, and 1-antitrypsin (A1AT) deficiency. The clinical history was consistent with A1AT deficiency (1–3 ). The diagnosis should be confirmed by direct quantification of circulating A1AT by immunoassay and confirmation of the presence of A1AT disease alelles by isoelectrofocusing and/or genotyping (2– 4 ). In this case, A1AT was not detectable and a Z/Z homozygote phenotype was found.