On the other hand, several other genes involved in CD40 signaling but acting in a B-cell-intrinsic manner (e.g., activation-induced cytidine deaminase (AICDA), uracil–DNA glycosylase (UNG), phosphatidylinositol 3-kinase catalytic delta (PIK3CD), and phosphatidylinositol 3-kinase regulatory subunit 1 alpha (PIK3R1)) may cause HIGM but have not been reported in association with Pjp. The gene discussed is AICDA; the disease is hyper-IgM syndrome type 1.