CD40 ligand deficiency

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

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.

Signs and symptoms

• Hoarse voice
• Decreased circulating IgG concentration
• Reduced total natural killer cell count
• Decreased class-switched memory B cell proportion
• Dysphonia
• Inverted CD4:CD8 ratio
• Recurrent otitis media
• Highly elevated creatine kinase
• Increased circulating IgM concentration
• Erythema

Also known as: HIGMX-1; X-linked hyper-IgM syndrome