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


Reviewed November 2006

What is the official name of the MT-TV gene?

The official name of this gene is “mitochondrially encoded tRNA valine.”

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

What is the normal function of the MT-TV gene?

The MT-TV gene provides instructions for making a particular type of RNA, a molecule that is a chemical cousin of DNA. This type of RNA, called transfer RNA (tRNA), helps assemble protein building blocks known as amino acids into full-length, functioning proteins. The MT-TV gene provides instructions for a specific form of transfer RNA that is designated as tRNAVal. This molecule attaches to a particular amino acid, valine (Val), and inserts it into the appropriate locations in many different proteins.

The tRNAVal molecule is present only in cellular structures called mitochondria. These structures convert energy from food into a form that cells can use. Through a process called oxidative phosphorylation, mitochondria use oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source. The tRNAVal molecule is involved in the assembly of proteins that carry out oxidative phosphorylation.

Does the MT-TV gene share characteristics with other genes?

The MT-TV gene belongs to a family of genes called TRNA (transfer RNAs).

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 MT-TV gene related to health conditions?

mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes - caused by mutations in the MT-TV gene

Mutations in the MT-TV gene are a very rare cause of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). Most cases of MELAS are caused by mutations in other mitochondrial genes, but a small number of cases resulting from mutations in the MT-TV gene have been reported. At least two mutations have been identified, each of which alters a single DNA building block (nucleotide) in the gene. One of these mutations replaces the nucleotide guanine with the nucleotide adenine at gene position 1642 (written as G1642A). Another mutation changes the nucleotide guanine to the nucleotide adenine at position 1644 (G1644A). Changes in the MT-TV gene may reduce the amount of tRNAVal available to assemble proteins within mitochondria. Because these proteins are needed for oxidative phosphorylation, MT-TV mutations may impair the ability of mitochondria to produce energy. Researchers have not determined how changes in mitochondrial energy production can lead to the specific features of MELAS.

other disorders - caused by mutations in the MT-TV gene

A few other mutations in the MT-TV gene have been have been reported, most of which change single nucleotides in the gene. These mutations are responsible for a variety of signs and symptoms chiefly affecting the muscles and nervous system. Medical problems associated with MT-TV mutations have included recurrent migraine headaches, muscle weakness and problems with movement, poor coordination, seizures, hearing loss, learning disabilities, and loss of intellectual function (dementia). A heart condition called cardiomyopathy, which weakens and enlarges the heart muscle, also has been reported in a small number of affected individuals.

Changes in the MT-TV gene have been identified as a rare cause of Leigh syndrome, a progressive brain disorder that typically appears in infancy or early childhood. In a few cases, MT-TV mutations were found in people with signs and symptoms that did not appear until adulthood. Affected individuals may experience vomiting, seizures, delayed development, muscle weakness, and problems with movement. Heart disease, kidney problems, and difficulty breathing can also occur in people with this disorder.

It is unclear why changes in the MT-TV gene can cause such a large variety of signs and symptoms. Even within a single family, affected individuals may have different health problems caused by the same genetic change.

Where is the MT-TV gene located?

The MT-TV gene is located in mitochondrial DNA.

Molecular Location in mitochondrial DNA: base pairs 1,602 to 1,670

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

Overview of gene located on mitochondrial DNA Close-up of gene located on mitochondrial DNA

Where can I find additional information about MT-TV?

You and your healthcare professional may find the following resources about MT-TV 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 MT-TV gene or gene products?

  • MTTV
  • tRNA valine
  • tRNA-Val, mitochondrial

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

What glossary definitions help with understanding MT-TV?

acidosis ; acids ; adenine ; adenosine triphosphate ; amino acid ; ATP ; cardiomyopathy ; cell ; dementia ; disabilities ; DNA ; gene ; guanine ; kidney ; lactic acidosis ; migraine ; mitochondria ; molecule ; mutation ; nervous system ; nucleotide ; oxidative phosphorylation ; oxygen ; phosphorylation ; protein ; RNA ; syndrome ; transfer RNA ; tRNA ; Val ; valine

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


  • Blakely EL, Poulton J, Pike M, Wojnarowska F, Turnbull DM, McFarland R, Taylor RW. Childhood neurological presentation of a novel mitochondrial tRNA(Val) gene mutation. J Neurol Sci. 2004 Oct 15;225(1-2):99-103. (
  • Chalmers RM, Lamont PJ, Nelson I, Ellison DW, Thomas NH, Harding AE, Hammans SR. A mitochondrial DNA tRNA(Val) point mutation associated with adult-onset Leigh syndrome. Neurology. 1997 Aug;49(2):589-92. (
  • de Coo IF, Sistermans EA, de Wijs IJ, Catsman-Berrevoets C, Busch HF, Scholte HR, de Klerk JB, van Oost BA, Smeets HJ. A mitochondrial tRNA(Val) gene mutation (G1642A) in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes. Neurology. 1998 Jan;50(1):293-5. (
  • Menotti F, Brega A, Diegoli M, Grasso M, Modena MG, Arbustini E. A novel mtDNA point mutation in tRNA(Val) is associated with hypertrophic cardiomyopathy and MELAS. Ital Heart J. 2004 Jun;5(6):460-5. (
  • NCBI Gene (
  • Taylor RW, Chinnery PF, Haldane F, Morris AA, Bindoff LA, Wilson J, Turnbull DM. MELAS associated with a mutation in the valine transfer RNA gene of mitochondrial DNA. Ann Neurol. 1996 Sep;40(3):459-62. (
  • Tiranti V, D'Agruma L, Pareyson D, Mora M, Carrara F, Zelante L, Gasparini P, Zeviani M. A novel mutation in the mitochondrial tRNA(Val) gene associated with a complex neurological presentation. Ann Neurol. 1998 Jan;43(1):98-101. (


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: November 2006
Published: February 8, 2016