STXBP2 and infection: In a clinical setting, the impaired GC formation and reduced isotype-switching in Stx11 deficiency resulting in variable hypogammaglobulinemia, as discovered in this study, is expected to increase susceptibility to infections, which is also described for late-onset FHL-5 patients with hypomorphic mutations in STXBP2, a direct interaction partner of STX11 (Rohr et al., 2010; Meeths et al., 2010; Pagel et al., 2012; Esmaeilzadeh et al., 2015).