In IgG4-ND, other anti-B cell agents that target CD19/20, especially those that concurrently activate the inhibitory FcγRIIb receptors (which IgG4 antibodies cannot bind to) thereby affecting functional blockade of CD19 without cell lysis such as obexelimab, can be even more beneficial as proposed in IgG4-related disease (NCT02725476) [214, 215]. This evidence concerns the gene CD19 and Norrie disease.