<unk>  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.
Hyper-IgM syndrome type 3
Hyper-IgM syndrome type 5
Hyper-IgM syndrome type 2
Hyper-IgM syndrome type 1
Hyper-IgM syndrome type 4
Hyper IgM syndrome
Anti-IgLON5 disease
Wiskott–Aldrich syndrome