Term Name:	CD40 ligand deficiency
Synonyms:	HIGMX-1, X-linked hyper-IgM syndrome
Definition:	A combined T cell and B cell immunodeficiency that is a X-linked immunodeficiency with hyperimmunoglobulin M (XHIM) affecting isotype switching and is caused by the absence of CD40 ligand which is normally expressed on activated CD4+ T cells. Individuals with this mutation are unable to switch from IgM to IgG, IgA and IgE.
Ontology:	Human Disease [DOID:0060022]   ( DOID:0060022 )