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POLR1D gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

POLR1D gene

The POLR1D gene encodes a subunit of RNA polymerase I and III, which are essential for RNA synthesis and the development of facial structures.

Normal Function

The POLR1D 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 POLR1D 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 20 mutations in the POLR1D 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 POLR1D 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

  • AC19
  • DNA-directed RNA polymerase I subunit D
  • DNA-directed RNA polymerases I and III subunit RPAC2
  • FLJ20616
  • MGC9850
  • polymerase (RNA) I polypeptide D
  • polymerase (RNA) I polypeptide D, 16kDa
  • polymerase (RNA) I subunit D
  • RNA polymerase I subunit D
  • RNA polymerases I and III subunit AC2
  • RPA16
  • RPA9
  • RPAC2
  • RPAC2_HUMAN
  • RPC16
  • RPO1-3

Genomic Location

The POLR1D gene is found on chromosome 13.

Frequently Asked Questions

Treatment is usually multidisciplinary. Surgical procedures may be needed to correct jaw size, ear structure, and eye socket depth. Early interventions can improve breathing and feeding. Cosmetic surgery and reconstructive procedures are often performed in adolescence or adulthood to address aesthetic concerns. Speech therapy and hearing evaluations are also common.
clinical evaluation by a geneticist or craniofacial specialist is the first step. If the physical findings suggest the condition, a DNA test that looks for mutations in the POLR1D gene (and sometimes other related genes like POLR1C) is performed. The test can be a targeted sequencing panel or whole-exome sequencing, and it identifies specific pathogenic variants that confirm the diagnosis.
genetic counselor will review the family history, explain the inheritance pattern (autosomal dominant with variable expression), and discuss recurrence risks. They will also talk about options such as prenatal testing (amniocentesis or chorionic villus sampling) or preimplantation genetic diagnosis if the couple wishes to avoid passing the mutation to future children.
In many cases, the most noticeable early signs include a small lower jaw (micrognathia), underdeveloped cheekbones, and a cleft or shallow upper lip. Some infants may also have a small or absent chin and a slight downward slant of the outer corners of the eyes. These features are often apparent at birth or within the first few weeks of life.
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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