This phenotype has not previously been reported in Sh2b3−/− mice, but the loss of MZ B cells has; although a decrease in MZ B cells has been observed in lupus-prone B6.Yaa mice, this was cell-extrinsic as a result of enhanced activation by antigen-bearing DCs (Santiago-Raber et al., 2010). Here, SH2B3 is linked to systemic lupus erythematosus.