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MT-TS1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MT-TS1 gene

The MT-TS1 gene provides instructions for creating a specific transfer RNA molecule essential for mitochondrial energy production, with mutations linked to various neurological and muscular disorders.

Normal Function

The MT-TS1 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-TS1 gene provides instructions for a specific form of tRNA that is designated as tRNASer(UCN). During protein assembly, this molecule attaches to a particular amino acid, serine (Ser), and inserts it into the appropriate locations in the growing protein.

The tRNASer(UCN) molecule is present 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, simple sugars, and fatty acids to create adenosine triphosphate (ATP), the cell's main energy source. The tRNASer(UCN) molecule is involved in the assembly of proteins that carry out oxidative phosphorylation.

Health Conditions Related to Genetic Changes

Myoclonic epilepsy with ragged-red fibers

Mutations in the MT-TS1 gene have been found in a few people with variant forms of myoclonic epilepsy with ragged-red fibers (MERRF). In these cases, affected individuals typically have:

  • Muscle twitches (myoclonus)
  • Muscle weakness (myopathy)
  • Difficulty coordinating movement (ataxia)
  • Hearing loss
  • Seizures
  • Intellectual impairment

Two mutations in the MT-TS1 gene have been found to cause these symptoms: one replaces the nucleotide thymine with cytosine at position 7512 (T7512C), and the other inserts an extra cytosine at position 7472 (7472insC).

Nonsyndromic hearing loss

The MT-TS1 gene is associated with cases of nonsyndromic hearing loss.

Palmoplantar keratoderma with deafness

Some MT-TS1 mutations cause a skin condition called palmoplantar keratoderma with deafness. In addition to hearing loss, this condition causes skin on the palms of the hands and the soles of the feet to become thick, scaly, and calloused. This is typically caused by the A7445G mutation, which disrupts the production of tRNASer(UCN), thereby impairing mitochondrial ATP production.

Other disorders

Mutations in the MT-TS1 gene can also cause health problems unrelated to hearing loss, such as exercise intolerance characterized by muscle pain, weakness, and extreme fatigue. The A7497G mutation has been identified in these cases. Researchers believe that a combination of genetic and environmental factors determines whether a mutation leads to isolated hearing loss, syndromic features, or other unrelated symptoms.

Frequently Asked Questions

Mitochondrial transfer RNA mutations like those in MT-TS1 depend on heteroplasmy and tissue distribution. During embryonic division, mitochondria are randomly partitioned into daughter cells. Consequently, one sibling may have a high proportion of mutated mtDNA in their brain and skeletal muscle, developing myoclonus, seizures, and ataxia. Another family member may harbor the mutation predominantly in inner ear structures, developing only isolated hearing impairment, while someone with low overall mutation load may remain entirely asymptomatic.
Hearing loss linked to the MT-TS1 gene is sensorineural and results from damage to the sensory hair cells of the inner ear or the auditory nerve. It is usually bilateral and slowly progressive, often starting in the high-frequency ranges during late childhood or early adulthood before progressing to all speech frequencies. It can appear either as an isolated symptom (nonsyndromic hearing loss) or alongside neuromuscular issues as part of a variant MERRF syndrome.
Yes. Patients carrying mitochondrial tRNA mutations should exercise extreme caution with medications known to impair mitochondrial function. Aminoglycoside antibiotics (such as gentamicin, tobramycin, and amikacin) are known to interact with mitochondrial RNA and significantly accelerate or trigger profound ototoxicity and permanent hearing loss. Additionally, mitochondrial disease specialists often caution against valproic acid and certain antiretroviral agents due to the increased risk of hepatic and metabolic complications.
Yes. Blood cells turn over rapidly, and rapidly dividing tissues can naturally select against cells with high mutant mitochondrial DNA loads over time. If a patient displays strong clinical signs of mitochondrial myopathy or variant MERRF but blood sequencing is inconclusive or shows very low heteroplasmy, clinicians often test other tissues where the mutation load may be significantly higher, such as urinary epithelial cells, a buccal swab, or a skeletal muscle biopsy.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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