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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed April 2011

What is the official name of the MYH9 gene?

The official name of this gene is “myosin, heavy chain 9, non-muscle.”

MYH9 is the gene's official symbol. The MYH9 gene is also known by other names, listed below.

What is the normal function of the MYH9 gene?

The MYH9 gene provides instructions for making a protein called myosin-9. This protein is one part (subunit) of the myosin IIA protein.

There are three forms of myosin II, called myosin IIA, myosin IIB and myosin IIC. They play roles in cell movement (cell motility); maintenance of cell shape; and cytokinesis, which is the step in cell division when the fluid surrounding the nucleus (the cytoplasm) divides to form two separate cells. While some cells use more than one type of myosin II, certain blood cells such as platelets and white blood cells (leukocytes) use only myosin IIA.

Each type of myosin II protein consists of two heavy chains and four light chains. The heavy chains each have two parts: a head region and a tail region. The head region interacts with actin, a protein that is important for cell movement and shape. The long tail region interacts with other proteins, including the tail regions of other myosin proteins.

Does the MYH9 gene share characteristics with other genes?

The MYH9 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? ( in the Handbook.

How are changes in the MYH9 gene related to health conditions?

MYH9-related disorder - caused by mutations in the MYH9 gene

More than 45 mutations in the MYH9 gene have been found to cause MYH9-related disorder. This disorder is characterized by bleeding problems, hearing loss, kidney (renal) disease, and clouding of the lens of the eyes (cataracts). Most of the mutations that cause this condition change single protein building blocks (amino acids) in the myosin-9 protein. Mutations that are located near the head of the myosin protein tend to lead to a more severe disorder than mutations that are located toward the tail of the protein. Recurring mutations involving the amino acid arginine at position 702 in the protein tend to result in many problems, including a severely reduced amount of platelets (thrombocytopenia), early-onset renal disease, and hearing loss in infancy.

Mutations in the MYH9 gene lead to the production of a nonfunctional protein. A nonfunctional myosin-9 protein cannot properly interact with other subunits to form myosin IIA. Platelets, which only express myosin IIA, are most affected by a lack of functional myosin-9, accounting for the thrombocytopenia seen in all individuals with MYH9-related disorder.

Where is the MYH9 gene located?

Cytogenetic Location: 22q13.1

Molecular Location on chromosome 22: base pairs 36,281,277 to 36,388,067

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The MYH9 gene is located on the long (q) arm of chromosome 22 at position 13.1.

The MYH9 gene is located on the long (q) arm of chromosome 22 at position 13.1.

More precisely, the MYH9 gene is located from base pair 36,281,277 to base pair 36,388,067 on chromosome 22.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about MYH9?

You and your healthcare professional may find the following resources about MYH9 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 MYH9 gene or gene products?

  • cellular myosin heavy chain, type A
  • myosin-9
  • myosin heavy chain 9
  • myosin heavy chain, non-muscle IIa
  • NMMHC II-a
  • non-muscle myosin heavy chain A
  • nonmuscle myosin heavy chain II-A
  • non-muscle myosin heavy chain IIa

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding MYH9?

acids ; actin ; amino acid ; arginine ; cell ; cell division ; cytokinesis ; cytoplasm ; gene ; kidney ; myosin ; myosin heavy chain ; myosin II ; nucleus ; platelets ; protein ; renal ; renal disease ; subunit ; thrombocytopenia ; white blood cells

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


  • Althaus K, Greinacher A. MYH9-related platelet disorders. Semin Thromb Hemost. 2009 Mar;35(2):189-203. doi: 10.1055/s-0029-1220327. Epub 2009 Apr 30. Review. (
  • Kunishima S, Saito H. Advances in the understanding of MYH9 disorders. Curr Opin Hematol. 2010 Sep;17(5):405-10. doi: 10.1097/MOH.0b013e32833c069c. Review. (
  • NCBI Gene (
  • Sekine T, Konno M, Sasaki S, Moritani S, Miura T, Wong WS, Nishio H, Nishiguchi T, Ohuchi MY, Tsuchiya S, Matsuyama T, Kanegane H, Ida K, Miura K, Harita Y, Hattori M, Horita S, Igarashi T, Saito H, Kunishima S. Patients with Epstein-Fechtner syndromes owing to MYH9 R702 mutations develop progressive proteinuric renal disease. Kidney Int. 2010 Jul;78(2):207-14. doi: 10.1038/ki.2010.21. Epub 2010 Mar 3. (


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? ( in the Handbook.

Reviewed: April 2011
Published: February 8, 2016