hyper-IgM syndrome type 3 (MONDO_0011735, a Monarch Disease Ontology term) is a form of Hyper IgM syndrome characterized by mutations of the CD40 gene. In this type, Immature B cells cannot receive signal 2 from helper T cells which is necessary to mature into mature B cells. Also known as: CD40 hyper-IgM syndrome, HIGM3, hyper-IgM syndrome caused by mutation in CD40, hyper-IgM syndrome due to CD40 deficiency, immunodeficiency with hyper-IgM type 3, type 3 hyper-IgM immunodeficiency.