Your immune system is a complex network of cells, tissues, and organs that work together to defend against germs. It helps your body to recognize these “foreign” invaders. Then its job is to keep them out, or if it can’t, to find and destroy them.
If your immune system cannot do its job, the results can be serious. Disorders of the immune system include
- Allergy and asthma – immune responses to substances that are usually not harmful
- Immune deficiency diseases – disorders in which the immune system is missing one or more of its parts
- Autoimmune diseases – diseases causing your immune system to attack your own body’s cells and tissues by mistake
NIH: National Institute of Allergy and Infectious Diseases
X-linked hyper IgM syndrome is a condition that affects the immune system and occurs almost exclusively in males. People with this disorder have abnormal levels of proteins called antibodies or immunoglobulins. Antibodies help protect the body against infection by attaching to specific foreign particles and germs, marking them for destruction. There are several classes of antibodies, and each one has a different function in the immune system. Although the name of this condition implies that affected individuals always have high levels of immunoglobulin M (IgM), some people have normal levels of this antibody. People with X-linked hyper IgM syndrome have low levels of three other classes of antibodies: immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin E (IgE). The lack of certain antibody classes makes it difficult for people with this disorder to fight off infections.Individuals with X-linked hyper IgM syndrome begin to develop frequent infections in infancy and early childhood. Common infections include pneumonia, sinus infections (sinusitis), and ear infections (otitis). Infections often cause these children to have chronic diarrhea and they fail to gain weight and grow at the expected rate (failure to thrive). Some people with X-linked hyper IgM syndrome have low levels of white blood cells called neutrophils (neutropenia). Affected individuals may develop autoimmune disorders, neurologic complications from brain and spinal cord (central nervous system) infections, liver disease, and gastrointestinal tumors. They also have an increased risk of lymphoma, which is a cancer of immune system cells.The severity of X-linked hyper IgM syndrome varies among affected individuals, even among members of the same family. Without treatment, this condition can result in death during childhood or adolescence.