X-linked agammaglobulinemia

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X-linked agammaglobulinemia
Other namesX-linked hypogammaglobulinemia, Bruton type agammaglobulinemia, Bruton syndrome, sex-linked agammaglobulinemia [1] : 83 
X-linked recessive.svg
The disorder is passed on in an X-linked recessive pattern
Specialty Immunology   OOjs UI icon edit-ltr-progressive.svg

X-linked agammaglobulinemia (XLA) is a rare genetic disorder discovered in 1952 that affects the body's ability to fight infection. As the form of agammaglobulinemia that is X-linked, it is much more common in males. In people with XLA, the white blood cell formation process does not generate mature B cells, [2] which manifests as a complete or near-complete lack of proteins called gamma globulins, including antibodies, in their bloodstream. B cells are part of the immune system and normally manufacture antibodies (also called immunoglobulins), which defend the body from infections by sustaining a humoral immunity response. Patients with untreated XLA are prone to develop serious and even fatal infections. A mutation occurs at the Bruton's tyrosine kinase (Btk) gene that leads to a severe block in B cell development (at the pre-B cell to immature B cell stage) and a reduced immunoglobulin production in the serum. Btk is particularly responsible for mediating B cell development and maturation through a signaling effect on the B cell receptor BCR. Patients typically present in early childhood with recurrent infections, in particular with extracellular, encapsulated bacteria. [3] XLA is deemed to have a relatively low incidence of disease, with an occurrence rate of approximately 1 in 200,000 live births [4] and a frequency of about 1 in 100,000 [5] male newborns. It has no ethnic predisposition. XLA is treated by infusion of human antibody. Treatment with pooled gamma globulin cannot restore a functional population of B cells, but it is sufficient to reduce the severity and number of infections due to the passive immunity granted by the exogenous antibodies. [3]

Contents

XLA is caused by a mutation on the X chromosome (Xq21.3-q22) of a single gene identified in 1993 which produces an enzyme known as Bruton's tyrosine kinase, or Btk. [3] XLA was first characterized by Dr. Ogden Bruton in a ground-breaking research paper published in 1952 describing a boy unable to develop immunities to common childhood diseases and infections. [6] It is the first known immune deficiency, and is classified with other inherited (genetic) defects of the immune system, known as primary immunodeficiency disorders.

Signs and symptoms

Affects males 50% of the time if mother is a carrier for the gene. Children are generally asymptomatic until 6–9 months of age when maternal IgG decreases. Present with recurrent infections with Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, hepatitis virus, and enterovirus CNS infections. [7] Examination shows lymphoid hypoplasia (tonsils and adenoids, no splenomegaly or lymphadenopathy). There is significant decrease in all immunoglobulins.[ citation needed ]

Genetics

X-chromosome Human male karyotpe high resolution - X chromosome cropped.png
X-chromosome

Most antibodies are gamma globulins. Antibodies are made mainly by plasma cells, which are daughter cells of the B cell line. The Btk enzyme plays an essential role in the maturation of B cells in the bone marrow, and when mutated, immature pro-B lymphocytes are unable to develop into pre-B lymphocytes, which normally develop into mature (naive) B cells that leave the bone marrow into the blood stream.[ citation needed ]

The disorder is inherited in an X-linked recessive fashion (as the gene linked to it is on the X chromosome) and is almost entirely limited to the sons of asymptomatic female carriers. [3] This is because males have only one copy of the X chromosome, while females have two copies; one normal copy of an X chromosome can compensate for mutations in the other X chromosome, so they are less likely to be symptomatic.[ citation needed ]

There is 30–50% chance of XLA patients having a positive family history of genetic inheritance. The rest of the cases occur as random mutations. [4] If a carrier female gives birth to a male child, there is a 50% chance that the male will have XLA. A carrier female has a 25% chance overall of giving birth to an affected male child. An XLA patient will pass on the gene, and all of his daughters will be XLA carriers, meaning that any male grandchildren from an XLA patient's daughters have a 50% chance of inheriting XLA. A female XLA patient can arise only as the child of an XLA patient and a carrier mother. XLA can also rarely result from a spontaneous mutation in the fetus of a non-carrier mother.[ citation needed ]

Diagnosis

XLA diagnosis usually begins due to a history of recurrent infections, mostly in the respiratory tract, through childhood. This is due to humoral immunodeficiency. [4] The diagnosis is probable when blood tests show the complete lack of circulating B cells (determined by the B cell marker CD19 and/or CD20), as well as low levels of all antibody classes, including IgG, IgA, IgM, IgE and IgD. [3]

When XLA is suspected, it is possible to do a Western Blot test to determine whether the Btk protein is being expressed. Results of a genetic blood test confirm the diagnosis and will identify the specific Btk mutation, [3] however its cost prohibits its use in routine screening for all pregnancies. Women with an XLA patient in their family should seek genetic counseling before pregnancy. Although the symptoms of a XLA and other primary immune diseases (PID) include repeated and often severe infections, the average time for a diagnosis of a PID can be up to 10 years.[ citation needed ]

Treatment

The most common treatment for XLA is an intravenous infusion of immunoglobulin (IVIg, human IgG antibodies) every week, for life. IVIg is a human product extracted and pooled from thousands of blood donations. IVIg does not cure XLA but increases the patient's lifespan and quality of life, by generating passive immunity, and boosting the immune system. [3] With treatment, the number and severity of infections is reduced. With IVIg, XLA patients may live a relatively healthy life. A patient should attempt reaching a state where his IgG blood count exceeds 800 mg/kg. The dose is based on the patient's weight and IgG blood-count.[ citation needed ]

Muscle injections of immunoglobulin (IMIg) were common before IVIg was prevalent, but are less effective and much more painful; hence, IMIg is now uncommon. Subcutaneous treatment (SCIg) was recently approved by the U.S. Food and Drug Administration (FDA), which is recommended in cases of severe adverse reactions to the IVIg treatment.[ citation needed ]

Antibiotics are another common supplementary treatment. Local antibiotic treatment (drops, lotions) are preferred over systemic treatment (pills) for long-term treatment, if possible. One of the future prospects of XLA treatment is gene therapy, which could potentially cure XLA. Gene therapy technology is still in its infancy and may cause severe complications such as cancer and even death. Moreover, the long-term success and complications of this treatment are, as yet, unknown.[ citation needed ]

Other considerations

It is not recommended and dangerous for XLA patients to receive live attenuated vaccines such as live polio, or the measles, mumps, rubella (MMR vaccine). [3] Special emphasis is given to avoiding the oral live attenuated SABIN-type polio vaccine that has been reported to cause polio to XLA patients. Furthermore, it is not known if active vaccines in general have any beneficial effect on XLA patients as they lack normal ability to maintain immune memory.[ citation needed ]

XLA patients are specifically susceptible to viruses of the Enterovirus family, and mostly to: polio virus, coxsackie virus (hand, foot, and mouth disease) and Echoviruses. These may cause severe central nervous system conditions as chronic encephalitis, meningitis and death. An experimental anti-viral agent, pleconaril, is active against picornaviruses. XLA patients, however, are apparently immune to the Epstein-Barr virus (EBV), as they lack mature B cells (and so HLA co-receptors) needed for the viral infection. [8] Patients with XLA are also more likely to have a history of septic arthritis. [4]

It is not known if XLA patients are able to generate an allergic reaction, as they lack functional IgE antibodies. There is no special hazard for XLA patients in dealing with pets or outdoor activities. [3] Unlike in other primary immunodeficiencies XLA patients are at no greater risk for developing autoimmune illnesses.

Agammaglobulinemia (XLA) is similar to the primary immunodeficiency disorder Hypogammaglobulinemia (CVID), and their clinical conditions and treatment are almost identical. However, while XLA is a congenital disorder, with known genetic causes, CVID may occur in adulthood and its causes are not yet understood. In addition, to X-linked agammaglobulinemia a couple of autosomal recessive agammaglobulinemia gene mutations have been described including mutations in IGHM, [9] IGLL1, [10] CD79A/B, [11] [12] BLNK [13] and deletion of the deletion of the terminal 14q32.33 chromosom. [14]

XLA was also historically mistaken as Severe Combined Immunodeficiency (SCID), a much more severe immune deficiency ("Bubble boys").A strain of laboratory mouse, XID, is used to study XLA. These mice have a mutated version of the mouse Btk gene, and exhibit a similar, yet milder, immune deficiency as in XLA.[ citation needed ]

See also

Related Research Articles

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.

<span class="mw-page-title-main">X-linked recessive inheritance</span> Mode of inheritance

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 a problem with the immune system 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 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 foreign invaders, chronic lung disease, and inflammation and infection of the gastrointestinal tract. CVID affects males and females equally. The condition can be found in children or teens but is generally not diagnosed or recognized until adulthood. The average age of diagnosis is between 20 and 50. However, symptoms vary greatly between people. "Variable" refers to the heterogeneous clinical manifestations of this disorder, which include recurrent bacterial infections, increased risk for autoimmune disease and lymphoma, as well as gastrointestinal disease. CVID is a lifelong disease.

<span class="mw-page-title-main">X-linked severe combined immunodeficiency</span> Medical condition

X-linked severe combined immunodeficiency (X-SCID) is an immunodeficiency disorder in which the body produces very few T cells and NK cells.

<span class="mw-page-title-main">Bruton's tyrosine kinase</span> Kinase that plays a crucial role in B cell development.

Bruton's tyrosine kinase, also known as tyrosine-protein kinase BTK, is a tyrosine kinase that is encoded by the BTK gene in humans. BTK plays a crucial role in B cell development.

<span class="mw-page-title-main">Hyper IgM syndrome</span> Primary immune deficiency disorders

Hyper IgM syndrome describes a group of primary immune deficiency disorders characterized by defective CD40 signaling; via B cells affecting class switch recombination (CSR) and somatic hypermutation. Immunoglobulin (Ig) class switch recombination deficiencies are characterized by elevated serum Immunoglobulin M (IgM) levels and a considerable deficiency in Immunoglobulins G (IgG), A (IgA) and E (IgE). As a consequence, people with HIGM have decreased concentrations of serum IgG and IgA and normal or elevated IgM, leading to increased susceptibility to infections.

<span class="mw-page-title-main">Hyper-IgM syndrome type 2</span> Primary immune deficiency disorder

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.

<span class="mw-page-title-main">Hyper-IgM syndrome type 5</span> Primary immune deficiency disorder

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:

<span class="mw-page-title-main">Humoral immune deficiency</span> Medical condition

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.

<span class="mw-page-title-main">Hyper-IgM syndrome type 3</span> Primary immune deficiency disorder

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.

<span class="mw-page-title-main">Hyper-IgM syndrome type 4</span> Medical condition

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.

<span class="mw-page-title-main">BENTA disease</span> Medical condition

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.

<span class="mw-page-title-main">DOCK8 deficiency</span> Medical condition

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.

Granulomatous–lymphocytic interstitial lung disease (GLILD) is a lung complication of common variable immunodeficiency disorders (CVID). It is seen in approximately 15% of patients with CVID. It has been defined histologically as the presence of (non-caseating) granuloma and lymphoproliferation in the lung. However, as GLILD is often associated with other auto-immune features such as splenomegaly, adenopathy and cytopenias, a definition based on abnormalities on lung imaging together with evidence of granulomatous inflammation elsewhere has also been employed.

Nuclear factor-kappa B Essential Modulator (NEMO) deficiency syndrome is a rare type of primary immunodeficiency disease that has a highly variable set of symptoms and prognoses. It mainly affects the skin and immune system but has the potential to affect all parts of the body, including the lungs, urinary tract and gastrointestinal tract. It is a monogenetic disease caused by mutation in the IKBKG gene. NEMO is the modulator protein in the IKK inhibitor complex that, when activated, phosphorylates the inhibitor of the NF-κB transcription factors allowing for the translocation of transcription factors into the nucleus.

References

  1. ↑ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN   0-7216-2921-0.
  2. ↑ "X-linked Agammaglobulinemia: Immunodeficiency Disorders: Merck Manual Professional" . Retrieved 2008-03-01.
  3. 1 2 3 4 5 6 7 8 9 X-Linked Agammaglobulinemia Patient and Family Handbook for The Primary Immune Diseases. Third Edition. 2001. Published by the Immune Deficiency Foundation
  4. 1 2 3 4 Chun, Jin-Kyong; Lee, Taek Jin; Song, Jae Woo; Linton, John A; Kim, Dong Soo (2008-02-29). "Analysis of Clinical Presentations of Bruton Disease: A Review of 20 Years of Accumulated Data from Pediatric Patients at Severance Hospital". Yonsei Medical Journal. 49 (1): 28–36. doi:10.3349/ymj.2008.49.1.28. ISSN   0513-5796. PMC   2615253 . PMID   18306466.
  5. ↑ Mahmoudi, Massoud (2007). Allergy and Asthma: Practical Diagnosis and Management. McGraw-Hill Professional. ISBN   978-0-07-147173-2.
  6. ↑ Bruton OC (1952). "Agammaglobulinemia". Pediatrics. 9 (6): 722–8. doi:10.1542/peds.9.6.722. PMID   14929630. S2CID   245180200.. Reproduced in Buckley CR (1998). "Agammaglobulinemia, by Col. Ogden C. Bruton, MC, USA, Pediatrics, 1952;9:722-728". Pediatrics. 102 (1 Pt 2): 213–5. doi:10.1542/peds.102.S1.213. PMID   9651432.
  7. ↑ Grammatikos Alexandros, Donati Matthew, Johnston Sarah L., Gompels Mark M. Peripheral B Cell Deficiency and Predisposition to Viral Infections: The Paradigm of Immune Deficiencies. Frontiers in Immunology (12)2021 https://www.frontiersin.org/articles/10.3389/fimmu.2021.731643 DOI=10.3389/fimmu.2021.731643
  8. ↑ Faulkner GC, Burrows SR, Khanna R, Moss DJ, Bird AG, Crawford DH (February 1999). "X-Linked agammaglobulinemia patients are not infected with Epstein-Barr virus: implications for the biology of the virus". Journal of Virology. 73 (2): 1555–64. doi:10.1128/JVI.73.2.1555-1564.1999. PMC   103980 . PMID   9882361.
  9. ↑ "OMIM Entry - # 601495 - AGAMMAGLOBULINEMIA 1, AUTOSOMAL RECESSIVE; AGM1".
  10. ↑ "OMIM Entry - # 613500 - AGAMMAGLOBULINEMIA 2, AUTOSOMAL RECESSIVE; AGM2".
  11. ↑ "OMIM Entry - # 613501 - AGAMMAGLOBULINEMIA 3, AUTOSOMAL RECESSIVE; AGM3".
  12. ↑ "OMIM Entry - # 612692 - AGAMMAGLOBULINEMIA 6, AUTOSOMAL RECESSIVE; AGM6".
  13. ↑ "OMIM Entry - # 613502 - AGAMMAGLOBULINEMIA 4, AUTOSOMAL RECESSIVE; AGM4".
  14. ↑ Geier, Christoph (October 2017). "Terminal 14q32.33 deletion as a novel cause of agammaglobulinemia". Clinical Immunology. 183: 41–45. doi:10.1016/j.clim.2017.07.003. PMID   28705765.
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