At the final follow-up examination, 75% of our cohort suffered from a persistent IEI condition, and an unPAD diagnosis was confirmed in fifty percent of cases, whereas the other patients were reclassified as a selective IgM deficiency (16%), CVID (5%), selective IgA deficiency (3%), and IgG3 subclass deficiency (1%). This evidence concerns the gene IGHG3 and Decreased circulating total IgM.