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Genetics Home Reference: your guide to understanding genetic conditions
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BTK

Reviewed February 2012

What is the official name of the BTK gene?

The official name of this gene is “Bruton agammaglobulinemia tyrosine kinase.”

BTK is the gene's official symbol. The BTK gene is also known by other names, listed below.

What is the normal function of the BTK gene?

The BTK gene provides instructions for making a protein called Bruton tyrosine kinase (BTK), which is essential for the development and maturation of B cells. B cells are specialized white blood cells that help protect the body against infection. These cells can mature into cells that produce special proteins called antibodies or immunoglobulins. Antibodies attach to specific foreign particles and germs, marking them for destruction. The BTK protein transmits important chemical signals that instruct B cells to mature and produce antibodies.

Does the BTK gene share characteristics with other genes?

The BTK gene belongs to a family of genes called SH2 domain containing (SH2 domain containing).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.

How are changes in the BTK gene related to health conditions?

isolated growth hormone deficiency - caused by mutations in the BTK gene

A few mutations in the BTK gene have been found to cause isolated growth hormone deficiency type III, a condition characterized by slow growth, short stature, and a weakened immune system. Mutations that cause this condition lead to production of a nonfunctional version of the BTK protein. People with isolated growth hormone deficiency are prone to infections because they produce very few B cells and have a shortage of antibodies (agammaglobulinemia). A lack of the BTK protein is likely responsible for the immune system symptoms, but how a shortage of BTK protein causes short stature in affected individuals is unclear.

X-linked agammaglobulinemia - caused by mutations in the BTK gene

More than 600 different mutations in the BTK gene have been found to cause X-linked agammaglobulinemia (XLA). Most of these mutations result in the absence of the BTK protein. Other mutations change a single protein building block (amino acid), which probably leads to the production of an abnormal BTK protein that is quickly broken down in the cell. The absence of functional BTK protein blocks B cell development and leads to a lack of antibodies, causing an increased susceptibility to infections in people with XLA.

Some people with XLA have large DNA deletions that remove one end of the BTK gene and all of a neighboring gene known as TIMM8A. Mutations in TIMM8A cause deafness-dystonia-optic neuronopathy (DDON) syndrome, which is characterized by hearing loss, vision problems, a decline in intellectual function (dementia), and involuntary muscle tensing (dystonia) or difficulty coordinating movements (ataxia). Individuals with large DNA deletions that include the BTK gene and the TIMM8A gene have the signs and symptoms of both XLA and DDON syndrome.

Where is the BTK gene located?

Cytogenetic Location: Xq21.33-q22

Molecular Location on the X chromosome: base pairs 101,349,446 to 101,390,795

The BTK gene is located on the long (q) arm of the X chromosome between positions 21.33 and 22.

The BTK gene is located on the long (q) arm of the X chromosome between positions 21.33 and 22.

More precisely, the BTK gene is located from base pair 101,349,446 to base pair 101,390,795 on the X chromosome.

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.

Where can I find additional information about BTK?

You and your healthcare professional may find the following resources about BTK helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the BTK gene or gene products?

  • AGMX1
  • AT
  • ATK
  • BPK
  • Bruton's tyrosine kinase
  • BTK_HUMAN
  • dominant-negative kinase-deficient Bruton's tyrosine kinase
  • IMD1
  • MGC126261
  • MGC126262
  • PSCTK1
  • tyrosine-protein kinase BTK
  • XLA

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What glossary definitions help with understanding BTK?

amino acid ; ataxia ; cell ; deficiency ; dementia ; DNA ; dystonia ; gene ; growth hormone ; hormone ; immune system ; infection ; involuntary ; kinase ; protein ; short stature ; stature ; susceptibility ; syndrome ; tyrosine ; white blood cells

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

References

  • Alatzoglou KS, Dattani MT. Genetic causes and treatment of isolated growth hormone deficiency-an update. Nat Rev Endocrinol. 2010 Oct;6(10):562-76. doi: 10.1038/nrendo.2010.147. Review. (http://www.ncbi.nlm.nih.gov/pubmed/20852587?dopt=Abstract)
  • Broides A, Yang W, Conley ME. Genotype/phenotype correlations in X-linked agammaglobulinemia. Clin Immunol. 2006 Feb-Mar;118(2-3):195-200. Epub 2005 Nov 16. (http://www.ncbi.nlm.nih.gov/pubmed/16297664?dopt=Abstract)
  • Conley ME, Farmer DM, Dobbs AK, Howard V, Aiba Y, Shurtleff SA, Kurosaki T. A minimally hypomorphic mutation in Btk resulting in reduced B cell numbers but no clinical disease. Clin Exp Immunol. 2008 Apr;152(1):39-44. doi: 10.1111/j.1365-2249.2008.03593.x. Epub 2008 Jan 28. (http://www.ncbi.nlm.nih.gov/pubmed/18241230?dopt=Abstract)
  • Gene Review: X-Linked Agammaglobulinemia (http://www.ncbi.nlm.nih.gov/books/NBK1453)
  • Jyonouchi H, Geng L, Törüner GA, Vinekar K, Feng D, Fitzgerald-Bocarsly P. Monozygous twins with a microdeletion syndrome involving BTK, DDP1, and two other genes; evidence of intact dendritic cell development and TLR responses. Eur J Pediatr. 2008 Mar;167(3):317-21. Epub 2007 May 23. (http://www.ncbi.nlm.nih.gov/pubmed/17520285?dopt=Abstract)
  • Maas A, Hendriks RW. Role of Bruton's tyrosine kinase in B cell development. Dev Immunol. 2001;8(3-4):171-81. Review. (http://www.ncbi.nlm.nih.gov/pubmed/11785667?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/695)
  • Richter D, Conley ME, Rohrer J, Myers LA, Zahradka K, Kelecić J, Sertić J, Stavljenić-Rukavina A. A contiguous deletion syndrome of X-linked agammaglobulinemia and sensorineural deafness. Pediatr Allergy Immunol. 2001 Apr;12(2):107-11. (http://www.ncbi.nlm.nih.gov/pubmed/11338284?dopt=Abstract)
  • Sedivá A, Smith CI, Asplund AC, Hadac J, Janda A, Zeman J, Hansíková H, Dvoráková L, Mrázová L, Velbri S, Koehler C, Roesch K, Sullivan KE, Futatani T, Ochs HD. Contiguous X-chromosome deletion syndrome encompassing the BTK, TIMM8A, TAF7L, and DRP2 genes. J Clin Immunol. 2007 Nov;27(6):640-6. Epub 2007 Sep 12. (http://www.ncbi.nlm.nih.gov/pubmed/17851739?dopt=Abstract)
  • Väliaho J, Smith CI, Vihinen M. BTKbase: the mutation database for X-linked agammaglobulinemia. Hum Mutat. 2006 Dec;27(12):1209-17. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16969761?dopt=Abstract)
  • Wit JM, Kiess W, Mullis P. Genetic evaluation of short stature. Best Pract Res Clin Endocrinol Metab. 2011 Feb;25(1):1-17. doi: 10.1016/j.beem.2010.06.007. Review. (http://www.ncbi.nlm.nih.gov/pubmed/21396571?dopt=Abstract)

 

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: February 2012
Published: July 27, 2015