Prevalence of Alpha-1 Antitrypsin Deficiency in Chronic Obstructive Pulmonary Disease (COPD)

Inclusion Criteria: * Male and female adults at least 18 years of age able to understand and consent to the procedures of this protocol. * All races and ethnicities will be considered for this study. * Post-bronchodilator values for pulmonary function tests on the day of enrollment with an FEV1 \< 80% of predicted and FEV1/FVC \< 70% (at least GOLD stage II). * Subjects who have been tested for Alpha-1 in the past but do not know their genotype or phenotype may be included in this study. Note: For the inclusion criteria the investigators will use the patient's GOLD status, based on percent predicted (FEV1 \< 80% of predicted); however, after sending the absolute value of FEV1 to the Data Coordinating Center (DCC) the DCC will calculate the percent predicted using a standardized formula (NHANES III). For sites that do not use this predicted formula, the results obtained at the DCC may differ from those used for subject enrollment. (For example, a subject found to have an FEV1 of \<80% at the study site could have an FEV1 \> 80% when the DCC recalculates it). Enrollment will be based on the percent predicted at each study site. If necessary, the data from this small number of outliers will be analyzed separately. Exclusion Criteria: * Subjects in whom post-bronchodilator spirometry is not performed. * Subjects whose ordering physician has specifically requested that his patients not be considered for enrollment. * Patients who have been tested for Alpha-1 in the past and know their genotype or phenotype.