CD40LG


CD40LG

A gene on chromosome Xq26 that encodes of a protein expressed on the surface of T cells which regulates B-cell function by binding CD40 to the B-cell surface. CD40LG is critical for immunoglobulin class switching. 
Molecular pathology
A defect in CD40LG is associated with hyper IgM syndrome due to an inability to undergo class switch.