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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 2012

What is the official name of the TPM3 gene?

The official name of this gene is “tropomyosin 3.”

TPM3 is the gene's official symbol. The TPM3 gene is also known by other names, listed below.

What is the normal function of the TPM3 gene?

The TPM3 gene provides instructions for making a protein called slow muscle alpha (α)-tropomyosin, which is part of the tropomyosin protein family. Tropomyosin proteins regulate the tensing of muscle fibers (muscle contraction) by controlling the binding of two muscle proteins, myosin and actin. In non-muscle cells, tropomyosin proteins play a role in controlling cell shape.

Slow muscle α-tropomyosin is found in skeletal muscles, which are the muscles used for movement. Skeletal muscle is made up of two types of muscle fibers: type I (slow twitch fibers) and type II (fast twitch fibers). Slow muscle α-tropomyosin is found only in type I fibers. Type I fibers are the primary component of skeletal muscles that are resistant to fatigue. For example, muscles involved in posture, such as the neck muscles that hold the head steady, are made predominantly of type I fibers. Slow muscle α-tropomyosin helps regulate muscle contraction in type I skeletal muscle fibers.

How are changes in the TPM3 gene related to health conditions?

cap myopathy - caused by mutations in the TPM3 gene

At least two TPM3 gene mutations have been identified in people with cap myopathy. These mutations replace the protein building block (amino acid) arginine with the amino acids cysteine or histidine at position 168 of the protein sequence, written as Arg168Cys or Arg168His (also written as R168C or R168H). The specific effects of these TPM3 gene mutations are unclear, but researchers suggest they may interfere with normal actin-myosin binding, impairing muscle contraction and resulting in the muscle weakness that occurs in cap myopathy.

congenital fiber-type disproportion - caused by mutations in the TPM3 gene

At least 10 mutations in the TPM3 gene have been found to cause congenital fiber-type disproportion. TPM3 gene mutations appear to be the most common cause of this disorder. These mutations change single amino acids in slow muscle α-tropomyosin. The TPM3 gene mutations that cause congenital fiber-type disproportion are thought to impair the protein's ability to interact with myosin and actin within type I skeletal muscle fibers, disrupting muscle contraction. Inefficient muscle contraction leads to muscle weakness and the other features of congenital fiber-type disproportion.

other disorders - caused by mutations in the TPM3 gene

Mutations in the TPM3 gene are also associated with a condition called nemaline myopathy. People with nemaline myopathy typically have muscle weakness throughout their body, including the muscles of the face, neck, and limbs. When nemaline myopathy is caused by mutations in the TPM3 gene, affected individuals typically have muscle weakness at birth or beginning in early childhood. TPM3 gene mutations account for a small percentage of all cases of nemaline myopathy.

Where is the TPM3 gene located?

Cytogenetic Location: 1q21.2

Molecular Location on chromosome 1: base pairs 154,155,303 to 154,192,134

The TPM3 gene is located on the long (q) arm of chromosome 1 at position 21.2.

The TPM3 gene is located on the long (q) arm of chromosome 1 at position 21.2.

More precisely, the TPM3 gene is located from base pair 154,155,303 to base pair 154,192,134 on chromosome 1.

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

Where can I find additional information about TPM3?

You and your healthcare professional may find the following resources about TPM3 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 TPM3 gene or gene products?

  • cytoskeletal tropomyosin TM30
  • FLJ41118
  • heat-stable cytoskeletal protein 30 kDa
  • hscp30
  • TM3
  • TM-5
  • TRK
  • tropomyosin alpha-3 chain
  • tropomyosin gamma

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

What glossary definitions help with understanding TPM3?

acids ; actin ; amino acid ; arginine ; cell ; congenital ; contraction ; cysteine ; gene ; histidine ; muscle cells ; myosin ; protein ; protein sequence ; skeletal muscle ; type I skeletal muscle fibers

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


  • Clarke NF, Kolski H, Dye DE, Lim E, Smith RL, Patel R, Fahey MC, Bellance R, Romero NB, Johnson ES, Labarre-Vila A, Monnier N, Laing NG, North KN. Mutations in TPM3 are a common cause of congenital fiber type disproportion. Ann Neurol. 2008 Mar;63(3):329-37. doi: 10.1002/ana.21308. (
  • De Paula AM, Franques J, Fernandez C, Monnier N, Lunardi J, Pellissier JF, Figarella-Branger D, Pouget J. A TPM3 mutation causing cap myopathy. Neuromuscul Disord. 2009 Oct;19(10):685-8. doi: 10.1016/j.nmd.2009.06.365. Epub 2009 Jun 23. (
  • Gene Review: Congenital Fiber-Type Disproportion (
  • Gene Review: Nemaline Myopathy (
  • Imoto C, Nonaka I. The significance of type 1 fiber atrophy (hypotrophy) in childhood neuromuscular disorders. Brain Dev. 2001 Aug;23(5):298-302. (
  • Laing NG, Wilton SD, Akkari PA, Dorosz S, Boundy K, Kneebone C, Blumbergs P, White S, Watkins H, Love DR, et al. A mutation in the alpha tropomyosin gene TPM3 associated with autosomal dominant nemaline myopathy. Nat Genet. 1995 Jan;9(1):75-9. Erratum in: Nat Genet. 1995 Jun;10(2):249. (
  • Lawlor MW, Dechene ET, Roumm E, Geggel AS, Moghadaszadeh B, Beggs AH. Mutations of tropomyosin 3 (TPM3) are common and associated with type 1 myofiber hypotrophy in congenital fiber type disproportion. Hum Mutat. 2010 Feb;31(2):176-83. doi: 10.1002/humu.21157. (
  • NCBI Gene (
  • Ochala J. Thin filament proteins mutations associated with skeletal myopathies: defective regulation of muscle contraction. J Mol Med (Berl). 2008 Nov;86(11):1197-204. doi: 10.1007/s00109-008-0380-9. Epub 2008 Jun 24. Review. (
  • Waddell LB, Kreissl M, Kornberg A, Kennedy P, McLean C, Labarre-Vila A, Monnier N, North KN, Clarke NF. Evidence for a dominant negative disease mechanism in cap myopathy due to TPM3. Neuromuscul Disord. 2010 Jul;20(7):464-6. doi: 10.1016/j.nmd.2010.05.012. Epub 2010 Jun 15. (


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 2012
Published: October 5, 2015