On the other hand, it should not be forgotten that there is a major pool of patients initially diagnosed with “CVID” who, after performing the genetic study, present a pathogenic variant of the established monogenic IEI (34–41), such as the case of NFKB1 haploinsufficiency or activated PI3K delta syndrome (described below). The gene discussed is NFKB1; the disease is common variable immunodeficiency.