NFKB2 and agammaglobulinemia: NF-κB2 deficiency. Inactivating mutations in NFKB2 encoding NF-κB2 (p100/p52) were initially identified in individuals who presented with hypogammaglobulinemia with or without endocrine or autoimmune features (Brue et al., 2014; Chen et al., 2013; Lee et al., 2014; Liu et al., 2014; Fig. 3).