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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed October 2008

What is the official name of the CD40LG gene?

The official name of this gene is “CD40 ligand.”

CD40LG is the gene's official symbol. The CD40LG gene is also known by other names, listed below.

What is the normal function of the CD40LG gene?

The CD40LG gene provides instructions for making a protein called CD40 ligand, which is found on the surface of immune system cells known as T cells. CD40 ligand attaches like a key in a lock to its receptor protein, CD40, which is located on the surface of immune system cells known as B cells. B cells are involved in the production of proteins called antibodies or immunoglobulins that help protect the body against infection. There are several classes of antibodies, and each one has a different function in the immune system. B cells are able to mature into the cells that produce immunoglobulin M (IgM) without any signals from other cells. In order for B cells to mature into the cells that produce antibodies of a different class, the CD40 receptor must interact with CD40 ligand. When these two proteins are connected, they trigger a series of chemical signals that instruct the B cell to start making immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin E (IgE).

CD40 ligand is also necessary for T cells to interact with other cells of the immune system, and it plays a key role in T cell differentiation (the process by which cells mature to carry out specific functions).

Does the CD40LG gene share characteristics with other genes?

The CD40LG gene belongs to a family of genes called CD (CD molecules). It also belongs to a family of genes called TNFSF (tumor necrosis factor (ligand) superfamily).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the CD40LG gene related to health conditions?

X-linked hyper IgM syndrome - caused by mutations in the CD40LG gene

More than 150 mutations in the CD40LG gene have been found to cause X-linked hyper IgM syndrome. These mutations lead to the production of an abnormal CD40 ligand or prevent production of this protein. If CD40 ligand does not attach to its receptor on B cells, these cells cannot produce IgG, IgA, or IgE antibodies. Mutations in the CD40LG gene also impair the T cell's ability to differentiate and interact with immune system cells. People with X-linked hyper IgM syndrome are more susceptible to infections because they do not have a properly functioning immune system.

Where is the CD40LG gene located?

Cytogenetic Location: Xq26

Molecular Location on the X chromosome: base pairs 136,648,177 to 136,660,390

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The CD40LG gene is located on the long (q) arm of the X chromosome at position 26.

The CD40LG gene is located on the long (q) arm of the X chromosome at position 26.

More precisely, the CD40LG gene is located from base pair 136,648,177 to base pair 136,660,390 on the X chromosome.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about CD40LG?

You and your healthcare professional may find the following resources about CD40LG helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the CD40LG gene or gene products?

  • CD40 antigen ligand
  • CD40L
  • CD154
  • gp39
  • hCD40L
  • HIGM1
  • IGM
  • IMD3
  • T-BAM
  • T-B cell-activating molecule
  • TNF-related activation protein
  • TNFSF5
  • TRAP
  • tumor necrosis factor (ligand) superfamily member 5

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding CD40LG?

cell ; class ; differentiation ; gene ; immune system ; immunoglobulin ; infection ; ligand ; molecule ; necrosis ; protein ; receptor ; syndrome ; tumor

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Bhushan A, Covey LR. CD40:CD40L interactions in X-linked and non-X-linked hyper-IgM syndromes. Immunol Res. 2001;24(3):311-24. Review. (
  • Durandy A. Hyper-IgM syndromes: a model for studying the regulation of class switch recombination and somatic hypermutation generation. Biochem Soc Trans. 2002 Aug;30(4):815-8. Review. (
  • Gene Review: X-Linked Hyper IgM Syndrome (
  • Gilmour KC, Walshe D, Heath S, Monaghan G, Loughlin S, Lester T, Norbury G, Cale CM. Immunological and genetic analysis of 65 patients with a clinical suspicion of X linked hyper-IgM. Mol Pathol. 2003 Oct;56(5):256-62. (
  • Jain A, Atkinson TP, Lipsky PE, Slater JE, Nelson DL, Strober W. Defects of T-cell effector function and post-thymic maturation in X-linked hyper-IgM syndrome. J Clin Invest. 1999 Apr;103(8):1151-8. (
  • NCBI Gene (
  • Notarangelo LD, Lanzi G, Peron S, Durandy A. Defects of class-switch recombination. J Allergy Clin Immunol. 2006 Apr;117(4):855-64. Review. (
  • Thusberg J, Vihinen M. The structural basis of hyper IgM deficiency - CD40L mutations. Protein Eng Des Sel. 2007 Mar;20(3):133-41. Epub 2007 Feb 16. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: October 2008
Published: February 8, 2016