Do you perform genetic testing when patients have persistent hypogammaglobulinemia after rituximab therapy?  

I would not routinely perform genetic testing. Multicenter studies (Labrosse et al., PMID 33862010; and Otttaviano et al., PMID 35892275) show that genetic testing returns a low yield, <5%. Several authors suggest that the risk of persistent hypogammaglobulinemia due to PID is increased if there ...

Yes, I do, but I also check immunoglobulins and perform genetic testing before I give rituximab.