Hyper igm syndrome

Hyper IgM syndrome (HIGM) is a group of immunodeficiency disorders which result in decreased levels of immunoglobulin A (IgA) and IgG in the blood, while levels of immunoglobulin M (IgM) are normal or elevated. This syndrome is caused by a defect in the T cells' ability to signal B cells to switch classes, leading to a lack of class-switched antibodies and an overproduction of IgM antibodies.

Causes

Hyper IgM syndrome is primarily caused by mutations in the CD40 ligand gene, which is located on the X chromosome. This gene provides instructions for making a protein found on the surface of activated T cells. The protein binds to the CD40 protein on B cells, which triggers B cells to switch from making IgM antibodies to making other types of antibodies. When the CD40 ligand gene is mutated, this process is disrupted, leading to the characteristic features of Hyper IgM syndrome.

Symptoms

The symptoms of Hyper IgM syndrome typically begin in infancy or early childhood. They can include frequent and severe bacterial infections, pneumonia, sinusitis, and ear infections. Individuals with this syndrome may also have an increased susceptibility to parasitic infections and autoimmune disorders, such as rheumatoid arthritis and lupus.

Diagnosis

Diagnosis of Hyper IgM syndrome is based on the presence of characteristic clinical features, a detailed patient history, a thorough clinical evaluation, and specialized laboratory testing. This can include measuring the levels of different types of immunoglobulins in the blood and genetic testing to identify mutations in the CD40 ligand gene.

Treatment

Treatment for Hyper IgM syndrome is aimed at managing the symptoms and preventing infections. This can include antibiotic therapy for bacterial infections, immunoglobulin replacement therapy to increase the levels of certain types of antibodies in the blood, and in severe cases, hematopoietic stem cell transplantation.

See also

• Primary immunodeficiency
• Immunoglobulin M
• CD40 ligand

NIH genetic and rare disease info

• NIH info on Hyper igm syndrome

Hyper igm syndrome is a rare disease.

Hyper igm syndrome Resources
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