CD40LG


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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.