Children with hyper-IgM syndrome have frequent sinus and lung infections.
Doctors diagnose the disorder by measuring levels of immunoglobulins in the blood and by doing genetic tests.
Treatment involves immune globulin, antibiotics to prevent infections, and, when possible, stem cell transplantation.
(See also Overview of Immunodeficiency Disorders Overview of Immunodeficiency Disorders Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual. Immunodeficiency... read more .)
IgM is one of 5 types of antibodies Antibodies One of the body's lines of defense ( immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more , which help defend the body against infection. The level of IgM is elevated or sometimes normal in hyper-IgM syndrome, but this is not the cause of the immunodeficiency. Other immunoglobulins Antibodies One of the body's lines of defense ( immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more are absent or at low levels. The lack of these other immunoglobulins makes people with hyper-IgM syndrome less able to fight off infection.
Hyper-IgM syndrome is a primary immunodeficiency disorder Primary immunodeficiency Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual. Immunodeficiency... read more . It may be inherited in one of the following ways:
As an X-linked disorder X-Linked Inheritance Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more : That is, it is due to a mutation in a gene on the X (sex) chromosome. X-linked disorders usually affect only boys.
As an autosomal recessive disorder Inheritance Patterns Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more : That is, two genes for the disorder, one from each parent, are required.
Most cases of hyper-IgM syndrome are X-linked.
How the disorder affects people varies depending on which gene is affected.
X-linked hyper-IgM syndrome
In X-linked hyper-IgM syndrome, B cells produce only IgM, not other types of immunoglobulin. Levels of IgM may be normal or high.
Infants with this form often develop pneumonia Pneumonia in Immunocompromised People Pneumonia is infection of the lungs. Pneumonia in people whose immune system is weakened or impaired (for example, by acquired immunodeficiency syndrome [AIDS], cancer, organ transplantation... read more due to the fungus Pneumocystis jirovecii. Children have frequent sinus and lung infections during the first 2 years of life.
Many children die before puberty, and those who live longer often develop cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more or lymphoma Overview of Lymphoma Lymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs. Lymphomas are cancers of a specific type of white blood cells known as lymphocytes. These... read more .
Autosomal recessive hyper-IgM syndrome
Generally, symptoms are similar to those of the X-linked form.
There are several autosomal recessive forms. In some of them, the lymph nodes, spleen, and tonsils are enlarged, and autoimmune disorders may develop.
Diagnosis of Hyper-IgM Syndrome
Doctors suspect hyper-IgM syndrome based on symptoms. They then measure levels of immunoglobulins. High or normal levels of IgM and low levels or absence of other immunoglobulins support the diagnosis.
When possible, the diagnosis is confirmed by genetic testing.
Prenatal genetic testing Prenatal Diagnostic Testing Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more can be offered to women considering pregnancy if they have family members with certain gene mutations that can cause hyper-IgM syndrome.
Treatment of Hyper-IgM Syndrome
Sometimes an antibiotic to prevent infections
Stem cell transplantation when possible
People with hyper-IgM syndrome are usually given immune globulin to replace some of the missing immunoglobulins. Immune globulin consists of antibodies obtained from the blood of people with a normal immune system.
Some people with some forms of this syndrome are given trimethoprim/sulfamethoxazole (an antibiotic) to prevent Pneumocystis jirovecii infection.
Stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more from a sibling with the same tissue type is done when possible.
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Immune Deficiency Foundation: Hyper-IgM syndrome: Comprehensive information on hyper-IgM syndrome, including information on diagnosis and treatment and advice for people affected