An Open-label, Multicenter Study to Assess the Pharmacokinetics (PK), Safety, and Tolerability of Subcutaneous IgPro20 in Immunoglobulin (IG) Treatment-naïve Participants With Primary Immunodeficiency (PID)

Inclusion Criteria: * \- Participants must be aged \>=18 years. * \- Participants must have a confirmed and documented diagnosis of PID, must be IG treatment-naïve and have an IgG level less than or equal to (\<=) 400 milligrams per deciliter(mg/dL) at Screening. Exclusion Criteria: * \- Participants with hyperprolinemia. * \- Participants who are receiving the following medications: * • Systemic corticosteroids (prednisone or equivalent; average daily dose of greater than \[\>\] 15 mg) from 4 weeks before Screening. * • Any dose of systemic immunosuppressants within 9 months or 5 times the half-life (t½) plus 6 months before Screening, whichever is longer. * • Any dose of biologic therapies with influence on the immune system (eg, tumor necrosis factor inhibitors, interleukin inhibitors, B-cell inhibitors), including investigational agents, within 12 months or 5 times the t½ plus 6 months before Screening, whichever is longer. * • Participants who are currently receiving anti-coagulation therapy. * \- Participants with hypoalbuminemia, protein-losing enteropathies, and kidney diseases with proteinuria. * \- Participants with a documented history or a current diagnosis of a thromboembolic event(s) (eg, deep vein thrombosis, pulmonary embolism, myocardial infarction, cerebrovascular accident, transient ischemic attack) or coagulopathy within 12 months before Screening. * \- Participants with severe dehydration and known blood disorders affecting viscosity. * \- Participants with aspartate aminotransferase and alanine aminotransferase concentration \> 3 times the upper limit of normal (ULN; central laboratory) at Screening. * \- Participants with creatinine concentration \> 1.5 times the ULN (central laboratory) at Screening. * \- Participants with new onset or worsening or severe cardiac, pulmonary, kidney disease, and liver disease. * \- Participants with malignancies of lymphoid cells such as chronic lymphocytic leukemia, non-Hodgkin's lymphoma, and immunodeficiency with thymoma.