Table 2.

Outstanding Therapeutic Questions.

If a microbiome is easily perturbed, could we deliberately alter it to favor a desired outcome of CVID patients? Can gut microbiome engineering lead to reduction of immune dysregulation in CVID patients? Can microbiome engineering in other niches (e.g., oral and upper respiratory tract) lead to control of immune dysregulation in CVID patients? Considering different phenotypes of CVID, which are likely to have advantages from microbiome engineering? Can the type of immunoglobulin replacement therapy (IgRT) (e.g., intravenous versus subcutaneous) affect the gut microbiome? Can the gut microbiome affect the short-term and long-term efficacy of subcutaneous or intravenous IgRT in CVID patients?