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POLR1C gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

POLR1C gene

The POLR1C gene provides instructions for creating a subunit of RNA polymerase I and III, enzymes critical for producing RNA and supporting early facial development.

Normal Function

The POLR1C gene provides instructions for making one part (subunit) of two related enzymes called RNA polymerase I and RNA polymerase III. These enzymes are involved in the production (synthesis) of ribonucleic acid (RNA), a chemical cousin of DNA. Both enzymes help synthesize a form of RNA known as ribosomal RNA (rRNA). RNA polymerase III also plays a role in the synthesis of several other forms of RNA, including transfer RNA (tRNA). Ribosomal RNA and transfer RNA assemble protein building blocks (amino acids) into functioning proteins, which is essential for the normal functioning and survival of cells.

Based on its involvement in Treacher Collins syndrome, the POLR1C gene appears to play a critical role in the early development of structures that become bones and other tissues of the face.

Health Conditions Related to Genetic Changes

Treacher Collins syndrome

At least six mutations in the POLR1C gene have been identified in people with Treacher Collins syndrome, a condition that affects the development of bones and other tissues of the face. These mutations appear to alter the structure and function of the POLR1C protein, which reduces the amount of functional RNA polymerase I and RNA polymerase III in cells. Consequently, less rRNA is produced. Researchers speculate that a shortage of rRNA may trigger the self-destruction (apoptosis) of certain cells involved in the early development of facial bones and tissues. The abnormal cell death could underlie the specific problems with facial development found in Treacher Collins syndrome. However, it is unclear why the effects of a reduction in rRNA are limited to facial development.

Coloboma

MedlinePlus Genetics provides information about Coloboma.

Other Names for This Gene

  • AC40
  • DNA-directed RNA polymerase I subunit C
  • DNA-directed RNA polymerases I and III 40 kDa polypeptide
  • DNA-directed RNA polymerases I and III subunit RPAC1
  • polymerase (RNA) I polypeptide C
  • polymerase (RNA) I polypeptide C, 30kDa
  • polymerase (RNA) I subunit C
  • RNA polymerase I subunit C
  • RNA polymerases I and III subunit AC1
  • RPA39
  • RPA40
  • RPA5
  • RPAC1
  • RPAC1_HUMAN
  • RPC40

Genomic Location

The POLR1C gene is found on chromosome 6.

Frequently Asked Questions

POLR1C mutations cause Treacher Collins syndrome in an autosomal dominant pattern. Each child of an affected parent has a 50 % chance of inheriting the mutation. However, some mutations arise de novo, so a parent may be unaffected while the child carries the mutation. Genetic counseling is recommended for families to understand recurrence risks and options such as pre‑implantation genetic diagnosis.===
Treatment is multidisciplinary and may include early reconstructive surgery to correct mandibular or maxillary deficiencies, ear reconstruction or prosthetics, and orthodontic care. Airway management may be necessary if the jaw or palate is severely underdeveloped. Speech therapy and hearing evaluations are also common supportive measures.
Typical signs include underdeveloped cheekbones (malar hypoplasia), downward‑slanted eye openings, a small lower jaw (micrognathia), ear abnormalities, and sometimes cleft palate. These features are usually apparent at birth or within the first few months of life. If a newborn shows a combination of these facial characteristics, genetic testing for POLR1C should be pursued.
The diagnosis is confirmed by sequencing the POLR1C gene from a blood or saliva sample. Targeted next‑generation sequencing panels for craniofacial disorders or whole‑exome sequencing can detect pathogenic variants. In some families, a family‑based linkage study may also be used.
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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