This is a longitudinal, observational, non-interventional registry study, designed to collect both retrospective and prospective data, in order to acquire real-world data on product prescribing, product use by patients, and product performance for patients receiving α1-PI therapy in a homecare and/or a Coram ambulatory infusion suite. There is no limit on the number of subjects that may participate in the registry. The AL1TER Registry will be overseen by the Principal Investigator listed on the first page of this protocol. No less than 40 physicians in the US will participate in this registry; there will be no upper limit to this number. All patients ≥18 years old, not members of a vulnerable study population, and who require α1-PI therapy may be invited to participate in this study.