Skip navigation

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

URL of this page:

CD40LG gene

CD40 ligand

Normal Function

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).

Health Conditions Related to Genetic Changes

X-linked hyper IgM syndrome

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.

More About This Health Condition

Other Names for This Gene

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

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Bhushan A, Covey LR. CD40:CD40L interactions in X-linked and non-X-linked hyper-IgM syndromes. Immunol Res. 2001;24(3):311-24. doi: 10.1385/IR:24:3:311. Citation on PubMed
  • Dunn CP, de la Morena MT. X-Linked Hyper IgM Syndrome. 2007 May 31 [updated 2020 Feb 20]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from Citation on PubMed
  • 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. doi: 10.1042/bst0300815. Citation on PubMed
  • 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. doi: 10.1136/mp.56.5.256. Citation on PubMed or Free article on PubMed Central
  • 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. doi: 10.1172/JCI5891. Citation on PubMed or Free article on PubMed Central
  • Notarangelo LD, Lanzi G, Peron S, Durandy A. Defects of class-switch recombination. J Allergy Clin Immunol. 2006 Apr;117(4):855-64. doi: 10.1016/j.jaci.2006.01.043. Citation on PubMed
  • Thusberg J, Vihinen M. The structural basis of hyper IgM deficiency - CD40L mutations. Protein Eng Des Sel. 2007 Mar;20(3):133-41. doi: 10.1093/protein/gzm004. Epub 2007 Feb 16. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.