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Genetics Home Reference: your guide to understanding genetic conditions
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MYO7A

Reviewed February 2007

What is the official name of the MYO7A gene?

The official name of this gene is “myosin VIIA.”

MYO7A is the gene's official symbol. The MYO7A gene is also known by other names, listed below.

What is the normal function of the MYO7A gene?

The MYO7A gene provides instructions for making a protein called myosin VIIA, which is part of a group of proteins called unconventional myosins. These proteins, which have similar structures, each play a role in transporting molecules within cells. Myosins interact with actin, a protein that is important for cell movement and shape. Researchers believe that myosins use long filaments of actin as tracks along which to transport other molecules.

Myosin VIIA is made primarily in the inner ear and the light-sensitive tissue at the back of the eye (the retina). In the inner ear, myosin VIIA plays a role in the development and maintenance of hairlike projections called stereocilia. Stereocilia, which are rich in actin, line the inner ear and bend in response to sound waves. This bending motion is critical for converting sound waves to nerve impulses.

Myosin VIIA is also found in the pigmented cells of the retina (the retinal pigment epithelium or RPE), and probably plays a similar role in the development and maintenance of this tissue. Research suggests that one function of myosin VIIA is to carry small sacs of pigment called melanosomes within the retinal pigment epithelium.

Does the MYO7A gene share characteristics with other genes?

The MYO7A gene belongs to a family of genes called myosins (myosins).

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 MYO7A gene related to health conditions?

nonsyndromic deafness - caused by mutations in the MYO7A gene

At least four mutations in the MYO7A gene have been identified in people with a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNA11. Autosomal dominant inheritance means that one altered copy of the gene in each cell is sufficient to cause the condition. Most of these mutations alter a single protein building block (amino acid) in myosin VIIA, resulting in an abnormal protein that does not work properly. Other genetic changes delete a small amount of DNA from critical regions of the MYO7A gene, which probably changes the structure of the protein. Researchers suspect that the altered protein causes hearing loss by disrupting the growth and organization of stereocilia in the inner ear.

A few studies have associated MYO7A mutations with an autosomal recessive form of nonsyndromic deafness called DFNB2. Autosomal recessive inheritance means that two copies of the gene in each cell are altered. Researchers suspect that these cases may actually represent early forms of Usher syndrome, which is characterized by hearing loss and a vision disorder called retinitis pigmentosa. It is not known whether all children with MYO7A mutations and hearing loss will develop retinitis pigmentosa later in life.

Usher syndrome - caused by mutations in the MYO7A gene

More than 120 mutations in the MYO7A gene have been identified in people with Usher syndrome type 1B. Many of these genetic changes alter a single protein building block (amino acid) in critical regions of the myosin VIIA protein. Other mutations introduce a premature stop signal in the instructions for the myosin VIIA protein. As a result, an abnormally small version of this protein is made. Some mutations insert or delete small amounts of DNA in the MYO7A gene, which alters the protein. All of these changes cause the production of a nonfunctional myosin VIIA protein that adversely affects the development and function of cells in the inner ear and retina, resulting in Usher syndrome.

Where is the MYO7A gene located?

Cytogenetic Location: 11q13.5

Molecular Location on chromosome 11: base pairs 77,128,255 to 77,215,240

The MYO7A gene is located on the long (q) arm of chromosome 11 at position 13.5.

The MYO7A gene is located on the long (q) arm of chromosome 11 at position 13.5.

More precisely, the MYO7A gene is located from base pair 77,128,255 to base pair 77,215,240 on chromosome 11.

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 MYO7A?

You and your healthcare professional may find the following resources about MYO7A 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 MYO7A gene or gene products?

  • deafness, autosomal dominant 11
  • deafness, autosomal recessive 2
  • DFNA11
  • DFNB2
  • MYO7A_HUMAN
  • myosin VIIA (Usher syndrome 1B (autosomal recessive, severe))
  • NSRD2
  • USH1B

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 MYO7A?

actin ; amino acid ; autosomal ; autosomal dominant ; autosomal recessive ; cell ; DNA ; epithelium ; gene ; inheritance ; myosin ; pigment ; protein ; recessive ; retina ; syndrome ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

  • Adato A, Kalinski H, Weil D, Chaib H, Korostishevsky M, Bonne-Tamir B. Possible interaction between USH1B and USH3 gene products as implied by apparent digenic deafness inheritance. Am J Hum Genet. 1999 Jul;65(1):261-5. (http://www.ncbi.nlm.nih.gov/pubmed/10364543?dopt=Abstract)
  • Adato A, Michel V, Kikkawa Y, Reiners J, Alagramam KN, Weil D, Yonekawa H, Wolfrum U, El-Amraoui A, Petit C. Interactions in the network of Usher syndrome type 1 proteins. Hum Mol Genet. 2005 Feb 1;14(3):347-56. Epub 2004 Dec 8. (http://www.ncbi.nlm.nih.gov/pubmed/15590703?dopt=Abstract)
  • Ahmed ZM, Riazuddin S, Riazuddin S, Wilcox ER. The molecular genetics of Usher syndrome. Clin Genet. 2003 Jun;63(6):431-44. Review. (http://www.ncbi.nlm.nih.gov/pubmed/12786748?dopt=Abstract)
  • Astuto LM, Bork JM, Weston MD, Askew JW, Fields RR, Orten DJ, Ohliger SJ, Riazuddin S, Morell RJ, Khan S, Riazuddin S, Kremer H, van Hauwe P, Moller CG, Cremers CW, Ayuso C, Heckenlively JR, Rohrschneider K, Spandau U, Greenberg J, Ramesar R, Reardon W, Bitoun P, Millan J, Legge R, Friedman TB, Kimberling WJ. CDH23 mutation and phenotype heterogeneity: a profile of 107 diverse families with Usher syndrome and nonsyndromic deafness. Am J Hum Genet. 2002 Aug;71(2):262-75. Epub 2002 Jun 19. (http://www.ncbi.nlm.nih.gov/pubmed/12075507?dopt=Abstract)
  • Bharadwaj AK, Kasztejna JP, Huq S, Berson EL, Dryja TP. Evaluation of the myosin VIIA gene and visual function in patients with Usher syndrome type I. Exp Eye Res. 2000 Aug;71(2):173-81. (http://www.ncbi.nlm.nih.gov/pubmed/10930322?dopt=Abstract)
  • Boëda B, El-Amraoui A, Bahloul A, Goodyear R, Daviet L, Blanchard S, Perfettini I, Fath KR, Shorte S, Reiners J, Houdusse A, Legrain P, Wolfrum U, Richardson G, Petit C. Myosin VIIa, harmonin and cadherin 23, three Usher I gene products that cooperate to shape the sensory hair cell bundle. EMBO J. 2002 Dec 16;21(24):6689-99. (http://www.ncbi.nlm.nih.gov/pubmed/12485990?dopt=Abstract)
  • Bolz H, Bolz SS, Schade G, Kothe C, Mohrmann G, Hess M, Gal A. Impaired calmodulin binding of myosin-7A causes autosomal dominant hearing loss (DFNA11). Hum Mutat. 2004 Sep;24(3):274-5. (http://www.ncbi.nlm.nih.gov/pubmed/15300860?dopt=Abstract)
  • El-Amraoui A, Petit C. Usher I syndrome: unravelling the mechanisms that underlie the cohesion of the growing hair bundle in inner ear sensory cells. J Cell Sci. 2005 Oct 15;118(Pt 20):4593-603. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16219682?dopt=Abstract)
  • Finsterer J, Fellinger J. Nuclear and mitochondrial genes mutated in nonsyndromic impaired hearing. Int J Pediatr Otorhinolaryngol. 2005 May;69(5):621-47. Review. (http://www.ncbi.nlm.nih.gov/pubmed/15850684?dopt=Abstract)
  • Gibbs D, Kitamoto J, Williams DS. Abnormal phagocytosis by retinal pigmented epithelium that lacks myosin VIIa, the Usher syndrome 1B protein. Proc Natl Acad Sci U S A. 2003 May 27;100(11):6481-6. Epub 2003 May 12. (http://www.ncbi.nlm.nih.gov/pubmed/12743369?dopt=Abstract)
  • Hasson T, Heintzelman MB, Santos-Sacchi J, Corey DP, Mooseker MS. Expression in cochlea and retina of myosin VIIa, the gene product defective in Usher syndrome type 1B. Proc Natl Acad Sci U S A. 1995 Oct 10;92(21):9815-9. (http://www.ncbi.nlm.nih.gov/pubmed/7568224?dopt=Abstract)
  • Keats BJ, Savas S. Genetic heterogeneity in Usher syndrome. Am J Med Genet A. 2004 Sep 15;130A(1):13-6. Review. (http://www.ncbi.nlm.nih.gov/pubmed/15368488?dopt=Abstract)
  • Liu XZ, Walsh J, Mburu P, Kendrick-Jones J, Cope MJ, Steel KP, Brown SD. Mutations in the myosin VIIA gene cause non-syndromic recessive deafness. Nat Genet. 1997 Jun;16(2):188-90. (http://www.ncbi.nlm.nih.gov/pubmed/9171832?dopt=Abstract)
  • OMIM: MYOSIN VIIA (http://omim.org/entry/276903)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/4647)
  • Petit C. Memorial lecture-hereditary sensory defects: from genes to pathogenesis. Am J Med Genet A. 2004 Sep 15;130A(1):3-7. (http://www.ncbi.nlm.nih.gov/pubmed/15368486?dopt=Abstract)
  • Petit C. Usher syndrome: from genetics to pathogenesis. Annu Rev Genomics Hum Genet. 2001;2:271-97. Review. (http://www.ncbi.nlm.nih.gov/pubmed/11701652?dopt=Abstract)
  • Reiners J, Nagel-Wolfrum K, Jürgens K, Märker T, Wolfrum U. Molecular basis of human Usher syndrome: deciphering the meshes of the Usher protein network provides insights into the pathomechanisms of the Usher disease. Exp Eye Res. 2006 Jul;83(1):97-119. Epub 2006 Mar 20. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16545802?dopt=Abstract)
  • Tamagawa Y, Ishikawa K, Ishikawa K, Ishida T, Kitamura K, Makino S, Tsuru T, Ichimura K. Phenotype of DFNA11: a nonsyndromic hearing loss caused by a myosin VIIA mutation. Laryngoscope. 2002 Feb;112(2):292-7. (http://www.ncbi.nlm.nih.gov/pubmed/11889386?dopt=Abstract)
  • Weil D, Blanchard S, Kaplan J, Guilford P, Gibson F, Walsh J, Mburu P, Varela A, Levilliers J, Weston MD, et al. Defective myosin VIIA gene responsible for Usher syndrome type 1B. Nature. 1995 Mar 2;374(6517):60-1. (http://www.ncbi.nlm.nih.gov/pubmed/7870171?dopt=Abstract)
  • Weil D, Küssel P, Blanchard S, Lévy G, Levi-Acobas F, Drira M, Ayadi H, Petit C. The autosomal recessive isolated deafness, DFNB2, and the Usher 1B syndrome are allelic defects of the myosin-VIIA gene. Nat Genet. 1997 Jun;16(2):191-3. (http://www.ncbi.nlm.nih.gov/pubmed/9171833?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 2007
Published: December 16, 2014