[Diagnosis of alpha-1 antitrypsin deficiency: limitations of rapid diagnostic laboratory tests].

Hereditary alpha-1-antitrypsin (α1-AT) deficiency predisposes to pulmonary emphysema. The objective of this study is to demonstrate the limitations of some laboratory methods used in the study of the deficiency, and which may produce errors in interpretation and detection of uncommon alleles. Two clinical cases are described: the index patient, who had pulmonary emphysema with α1-AT levels less than 12 mg/dL, was erroneously classified as a homozygote of the normal allelic variant PI MM using a rapid genotype method; the mother of the patient, asymptomatic, with low levels (60 mg/dL), was also classified as PI MM. The gene sequencing classified the index patient as a carrier of the PI Clayton null allele and PI Mmalton deficient. The mother was a PI Clayton/PI heterozygote carrier. These results highlight the difficulties in diagnosing the deficiency, as the well as the need to reach a consensus on methods for this study.