The actual prevalence of APDS-causing mutations among CVID patients is difficult to estimate, as genetic analysis in CVID patients is not worldwide uniformed; however, data from large cohorts’ genetic studies revealed that pathogenic PIK3CD or PIK3R1 mutations are found in approximately 1.4–7.1% of CVID patients [4,21,22]. This evidence concerns the gene PIK3R1 and common variable immunodeficiency.