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TRNT1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TRNT1 Gene: tRNA Nucleotidyl Transferase 1

The TRNT1 gene provides instructions for making a protein essential for modifying transfer RNA (tRNA), a process critical for protein synthesis in both the cytoplasm and mitochondria. Mutations in this gene can lead to TRNT1 deficiency, a multisystem disorder, and retinitis pigmentosa.

Normal Function

The TRNT1 gene provides instructions for making a protein involved in the production (synthesis) of other proteins. During protein synthesis, a molecule called transfer RNA (tRNA) helps assemble protein building blocks (amino acids) into a chain that forms the protein. Each tRNA carries a specific amino acid to the growing chain.

The TRNT1 protein modifies tRNAs by adding a series of three DNA building blocks (nucleotides), called a CCA trinucleotide, to the molecule. This modification is essential for the correct amino acid to be attached to each tRNA.

Role in Cytoplasm and Mitochondria

While most protein synthesis occurs in the fluid surrounding the nucleus (cytoplasm), some proteins are synthesized in cell structures called mitochondria, which are the energy-producing centers in cells. Many mitochondrial proteins form groups (complexes) that carry out the reactions that produce energy. Separate tRNA molecules are used to build proteins in the cytoplasm and mitochondria. The TRNT1 protein attaches the CCA trinucleotide to both cytoplasmic and mitochondrial tRNA molecules.

Health Conditions Related to Genetic Changes

TRNT1 Deficiency

More than 20 TRNT1 gene mutations have been found to cause TRNT1 deficiency, a condition with a range of signs and symptoms that affect many body systems. The severity of the condition varies among affected individuals. Features can include:

  • A blood disorder called sideroblastic anemia
  • Recurrent fevers
  • A shortage of immune cells called B cells that leads to impairment of the immune system (immunodeficiency)
  • Delayed development of speech and motor skills
  • Eye abnormalities that cause vision problems

The TRNT1 gene mutations that cause TRNT1 deficiency lead to a shortage (deficiency) of functional TRNT1 protein. As a result, the addition of the CCA trinucleotide to tRNA molecules is impaired. Researchers suspect that without the modification, tRNAs are less able to participate in protein synthesis. Studies show that deficiency of TRNT1 prevents the formation of certain mitochondrial protein complexes that are involved in energy production. It is unclear if cytoplasmic protein synthesis is also affected. The reduction of energy could damage cells in many body systems, leading to the varied signs and symptoms of TRNT1 deficiency. Researchers believe that mutations that cause a greater impairment of TRNT1 function lead to more severe signs and symptoms.

Retinitis Pigmentosa

Genetic changes in the TRNT1 gene are also associated with retinitis pigmentosa, a condition that affects the retina.

Other Names for This Gene

  • ATP(CTP):tRNA nucleotidyltransferase
  • CCA tRNA nucleotidyltransferase 1, mitochondrial isoform 1
  • CCA tRNA nucleotidyltransferase 1, mitochondrial isoform 2
  • CCA-adding enzyme
  • CCA1
  • CGI-47
  • mitochondrial CCA-adding tRNA-nucleotidyltransferase
  • mt CCA-adding enzyme
  • mt tRNA adenylyltransferase
  • mt tRNA CCA-diphosphorylase
  • mt tRNA CCA-pyrophosphorylase
  • MtCCA
  • RPEM
  • SIFD
  • tRNA CCA nucleotidyl transferase 1
  • tRNA nucleotidyl transferase, CCA-adding, 1
  • tRNA-nucleotidyltransferase 1, mitochondrial

Genomic Location

The TRNT1 gene is found on chromosome 3.

Frequently Asked Questions

Because TRNT1 adds the CCA tail to mitochondrial tRNAs, mutations can impair mitochondrial protein synthesis, leading to reduced cellular energy. Clinicians often monitor cardiac function (echocardiogram), liver enzymes, and muscle strength. Fatigue or exercise intolerance should be reported promptly, and periodic metabolic panels are advisable.
TRNT1 deficiency is inherited in an autosomal recessive pattern. Both parents must carry one pathogenic copy of the gene. Each pregnancy has a 25 % chance of producing an affected child, a 50 % chance of a carrier, and a 25 % chance of a child with two normal copies.
Diagnosis usually starts with clinical suspicion (e.g., sideroblastic anemia, recurrent fevers, immunodeficiency). Confirmatory testing involves targeted next‑generation sequencing or whole‑exome sequencing that includes the TRNT1 gene, followed by Sanger confirmation of identified variants.
Management is largely supportive. Regular transfusions may be needed for anemia, and iron chelation can prevent overload. Immunoglobulin replacement helps B‑cell deficiency, and prophylactic antibiotics reduce infection risk. Some patients benefit from hematopoietic stem‑cell transplantation, but eligibility depends on organ involvement and donor availability.
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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