Finally, although in rare cases, severe refractory urticaria has been described in association with IEI, potentially representing the first disease manifestation of CVID and a leading sign of the PLCG2-associated antibody deficiency and immune dysregulation (PLAID), thus highlighting the importance of an immunological assessment in selected patients presenting with urticaria (39, 40). Here, PLCG2 is linked to urticaria.