CD40 is a costimulatory receptor on B cells that, when bound to CD40 ligand (CD40L), sends a signal to the B-cell receptor. When there is a defect in CD40, this leads to defective T-cell interaction with B cells. Consequently, humoral immune response is affected. Patients are more susceptible to infection.
Hyper-IgM syndrome type 2
Hyper-IgM syndrome type 5
Hyper-IgM syndrome type 1
Hyper-IgM syndrome type 3
Hyper-IgM syndrome type 4
Hyper IgM syndrome
Anti-IgLON5 disease
Wiskott–Aldrich syndrome