Rituximab has been linked to reduced immunoglobulin levels: in the large RA group, 22.4 % of rituximab-treated patients developed low IgM and a smaller proportion developed low IgG (3.5 %) or low IgA (1.1 %) that persisted for at least 4 months [40]. The gene discussed is CD79A; the disease is rheumatoid arthritis.