- Eight or more new ear infections within 1 year
- Two or more serious sinus infections within 1 year
- Two or more months on antibiotics with little effect
- Two or more pneumonias within 1 year
- Failure of an infant to gain weight or grow normally
- Recurrent, deep skin, or organ abscesses
- Persistent thrush in mouth or elsewhere on skin, after age 1
- Need for intravenous antibiotics to clear infections
- Two or more deep-seated infections
- A family history of Primary Immunodeficiency