TNFRSF13B and hyperinsulinemic hypoglycemia, familial, 4: Barmettler et al. also observed a correlation between low CD4+ T-helper cells and low specific antibody responses in their mixed cohort of individuals with secondary and severe primary PADs, including complicated CVID/SpAD, activated P13K-syndrome, TACI deficiency, NFKB1 deficiency, HGG, and IgG subclass deficiency.