Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affect the patient's immune system. Examples of these extrinsic factors include HIV infection and environmental factors, such as nutrition. Immunocompromisation may also be due to genetic diseases/flaws such as SCID.
Adenosine deaminase deficiency is a metabolic disorder that causes immunodeficiency. It is caused by mutations in the ADA gene. It accounts for about 10–20% of all cases of autosomal recessive forms of severe combined immunodeficiency (SCID) after excluding disorders related to inbreeding.
X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males and in females who are homozygous for the gene mutation, see zygosity. Females with one copy of the mutated gene are carriers.
Hypogammaglobulinemia is an immune system disorder in which not enough gamma globulins are produced in the blood. This results in a lower antibody count, which impairs the immune system, increasing risk of infection. Hypogammaglobulinemia may result from a variety of primary genetic immune system defects, such as common variable immunodeficiency, or it may be caused by secondary effects such as medication, blood cancer, or poor nutrition, or loss of gamma globulins in urine, as in nonselective glomerular proteinuria. Patients with hypogammaglobulinemia have reduced immune function; important considerations include avoiding use of live vaccines, and take precautionary measures when traveling to regions with endemic disease or poor sanitation such as receiving immunizations, taking antibiotics abroad, drinking only safe or boiled water, arranging appropriate medical cover in advance of travel, and ensuring continuation of any immunoglobulin infusions needed.
Common variable immunodeficiency (CVID) is an inborn immune disorder characterized by recurrent infections and low antibody levels, specifically in immunoglobulin (Ig) types IgG, IgM, and IgA. Symptoms generally include high susceptibility to pathogens, chronic lung disease, as well as inflammation and infection of the gastrointestinal tract.
X-linked severe combined immunodeficiency (X-SCID) is an immunodeficiency disorder in which the body produces very few T cells and NK cells.
Selective immunoglobulin A (IgA) deficiency (SIgAD) is a kind of immunodeficiency, a type of hypogammaglobulinemia. People with this deficiency lack immunoglobulin A (IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract. It is defined as an undetectable serum IgA level in the presence of normal serum levels of IgG and IgM, in persons older than 4 years. It is the most common of the primary antibody deficiencies. Most such persons remain healthy throughout their lives and are never diagnosed.
Hyper IgM syndrome is a rare primary immune deficiency disorders characterized by low or absent levels of serum IgG, IgA, IgE and normal or increased levels of serum IgM.
Hyper IgM syndrome type 2 is a rare disease. Unlike other hyper-IgM syndromes, type 2 patients identified thus far did not present with a history of opportunistic infections. One would expect opportunistic infections in any immunodeficiency syndrome. The responsible genetic lesion is in the AICDA gene found at 12p13.
The fifth type of hyper-IgM syndrome has been characterized in three patients from France and Japan. The symptoms are similar to hyper IgM syndrome type 2, but the AICDA gene is intact.
Primary immunodeficiencies are disorders in which part of the body's immune system is missing or does not function normally. To be considered a primary immunodeficiency (PID), the immune deficiency must be inborn, not caused by secondary factors such as other disease, drug treatment, or environmental exposure to toxins. Most primary immunodeficiencies are genetic disorders; the majority are diagnosed in children under the age of one, although milder forms may not be recognized until adulthood. While there are over 430 recognized inborn errors of immunity (IEIs) as of 2019, the vast majority of which are PIDs, most are very rare. About 1 in 500 people in the United States are born with a primary immunodeficiency. Immune deficiencies can result in persistent or recurring infections, auto-inflammatory disorders, tumors, and disorders of various organs. There are currently limited treatments available for these conditions; most are specific to a particular type of PID. Research is currently evaluating the use of stem cell transplants (HSCT) and experimental gene therapies as avenues for treatment in limited subsets of PIDs.
An immune disorder is a dysfunction of the immune system. These disorders can be characterized in several different ways:
IgG deficiency is a form of dysgammaglobulinemia where the proportional levels of the IgG isotype are reduced relative to other immunoglobulin isotypes.
Humoral immune deficiencies are conditions which cause impairment of humoral immunity, which can lead to immunodeficiency. It can be mediated by insufficient number or function of B cells, the plasma cells they differentiate into, or the antibody secreted by the plasma cells. The most common such immunodeficiency is inherited selective IgA deficiency, occurring between 1 in 100 and 1 in 1000 persons, depending on population. They are associated with increased vulnerability to infection, but can be difficult to detect in the absence of infection.
Hyper-IgM syndrome type 3 is a form of hyper IgM syndrome characterized by mutations of the CD40 gene. In this type, Immature B cells cannot receive signal 2 from helper T cells which is necessary to mature into mature B cells.
Hyper-IgM syndrome type 4 is a form of Hyper IgM syndrome which is a defect in class switch recombination downstream of the AICDA gene that does not impair somatic hypermutation.
Hans Dieter Ochs, is an immunologist and pediatrician. He is Professor of Pediatrics, Division of Immunology, Department of Pediatrics, University of Washington School of Medicine, Seattle.
BENTA disease is a rare genetic disorder of the immune system. BENTA stands for "B cell expansion with NF-κB and T cell anergy" and is caused by germline heterozygous gain-of-function mutations in the gene CARD11. This disorder is characterized by polyclonal B cell lymphocytosis with onset in infancy, splenomegaly, lymphadenopathy, mild immunodeficiency, and increased risk of lymphoma. Investigators Andrew L. Snow and Michael J. Lenardo at the National Institute of Allergy and Infectious Diseases at the U.S. National Institutes of Health first characterized BENTA disease in 2012. Dr. Snow's current laboratory at the Uniformed Services University of the Health Sciences is now actively studying this disorder.
DOCK8 deficiency, also called DOCK8 immunodeficiency syndrome, is the autosomal recessive form of hyperimmunoglobulin E syndrome, a genetic disorder characterized by elevated immunoglobulin E levels, eosinophilia, and recurrent infections with staphylococcus and viruses. It is caused by a mutation in the DOCK8 gene.
An X-linked genetic disease is a disease inherited through a genetic defect on the X chromosome. In human cells, there is a pair of non-matching sex chromosomes, labelled X and Y. Females carry two X chromosomes, whereas males have one X and one Y chromosome. A disease or trait determined by a gene on the X chromosome demonstrates X-linked inheritance, which can be divided into dominant and recessive patterns.
