Four patients were excluded from further analysis due to either associated T-cell defects (one patient with DOCK8 deficiency) [6] or concurrent IgG subclass deficiencies (one individual with ADA2 deficiency [7], one with Claes-Jensen syndrome, and one with a clinical diagnosis of unclassified primary antibody deficiency). Here, ADA2 is linked to hyperinsulinemic hypoglycemia, familial, 4.