Despite that, mutations in the genes CR2, LRBA, NFKB1, NFKB2, IL21, TNFRSF13B, TNFRSF13C, CD81, IKZF1, PRKCD, MS4A1, and CD19 are listed in the OMIM database1 as causative of disease, inducing reclassification of CVID in these new diagnostics, and establishing new therapeutic approaches based on the affected pathways that have markedly improved affected patients’ prognoses (8). Here, IL21 is linked to common variable immunodeficiency.