X-linked agammaglobulinemia
00:00 / 00:00
Videos
Notes
X-linked agammaglobulinemia
Genetics
Genetics
Assessments
X-linked agammaglobulinemia
Flashcards
0 / 6 complete
USMLE® Step 1 questions
0 / 1 complete
High Yield Notes
10 pages
Flashcards
X-linked agammaglobulinemia
of complete
Questions
USMLE® Step 1 style questions USMLE
of complete
Memory Anchors and Partner Content
External References
First Aid
2022
2021
2020
2019
2018
2017
2016
Agammaglobulinemia
chromosome affected p. 62
Bruton agammaglobulinemia p. 59, 114
Hypogammaglobulinemia p. 221
Tonsils
agammaglobulinemia p. 114
X-linked agammaglobulinemia p. 114
X-linked recessive disorders
agammaglobulinemia p. 114
External Links
Transcript
Content Reviewers
Contributors
With X-linked agammaglobulinemia, or XLA for short, gamma globulin is another name for immunoglobulin, which is another name for antibodies, a- means without, and -emia refers to the blood.
So this is a disease where there aren’t any antibodies in the blood, and X-linked means that it’s caused by a gene mutation on the X chromosome.
Now, normally, immunoglobulins are secreted into the blood by plasma cells, which are fully matured or differentiated B cells, a type of immune cell.
Way before that ever happens, though, those B cells start out in the bone marrow as pluripotent stem cells, pluripotent meaning that they can develop into a number of different types of cells.
But to become a B cell, first that pluripotent stem cell differentiates into a lymphoid precursor cell, then a pro-B cell, then a pre-B cell, then an immature B cell which migrates from the bone marrow to the spleen, where it becomes a mature or naive B cell, which after being exposed to the right antigen, moves into the blood or lymph and becomes an antibody-secreting plasma cell.
In XLA, this maturation process stops at the pre-B cell stage.
Why does it do that? Well, by the immature B cell stage, it has a B cell receptor, which is a membrane-bound antibody, specifically an immunoglobulin M or IgM.
But in the Pre- and Pro-B cell stages, this B cell receptor’s still being assembled, once it’s finished, it’s made up of heavy chain and light chain protein subunits, and the heavy chains are put together first.
Since it hasn’t been fully assembled yet, this IgM’s known as a pre-B cell receptor.
Now, an enzyme called bruton’s tyrosine kinase is super important for both the development and normal functioning of the B cell receptor.
Summary
X-linked agammaglobulinemia (XLA) is an x-linked genetic disorder of the immune system caused by mutations in the BTK (Bruton's tyrosine kinase) gene. XLA primarily affects males, as they only have one X chromosome, while females have two and are typically carriers of the mutated gene. Individuals with XLA have a deficiency in B cells. This results in an inability to mount an effective immune response against bacterial infections, leading to recurrent and often severe infections, especially of the respiratory tract and ears. The symptoms of XLA typically appear in early childhood, and affected individuals may experience recurrent bacterial infections, chronic diarrhea, and failure to thrive.
Sources
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
- "Yen & Jaffe's Reproductive Endocrinology" Saunders W.B. (2018)
- "Bates' Guide to Physical Examination and History Taking" LWW (2016)
- "Robbins Basic Pathology" Elsevier (2017)
- "X-Linked Agammaglobulinemia Patients Are Not Infected with Epstein-Barr Virus: Implications for the Biology of the Virus" Journal of Virology (1999)
- "Autoimmunity in Primary Immunodeficiency Disorders: An Updated Review on Pathogenic and Clinical Implications" Journal of Clinical Medicine (2021)
- "Peripheral B Cell Deficiency and Predisposition to Viral Infections: The Paradigm of Immune Deficiencies" Frontiers in Immunology (2021)
- "B-cell biology and development" Journal of Allergy and Clinical Immunology (2013)
For Institutions
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.
