SH2B3 and systemic lupus erythematosus: Phenotyping of the three human SLE patients with rare variants in SH2B3 (one carrying Q540X and two carrying R566Q) (Fig. 1 A) using our established protocols (Ellyard et al., 2019) revealed a higher frequency of transitional B cells compared with HCs, which was also observed in other SLE patients (Fig. 3 F) and reported previously (Sims et al., 2005).