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ORC6 gene

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

ORC6 gene

The ORC6 gene is essential for DNA replication and cell division, providing instructions for a protein that helps initiate the copying of genetic material.

Normal Function

The ORC6 gene provides instructions for making a protein that is a subunit of the origin recognition complex (ORC). This complex, consisting of proteins ORC1 through ORC6, is vital for DNA replication. The ORC binds to specific DNA regions called origins of replication, where it recruits additional proteins to form a pre-replication complex. This process, known as replication licensing, ensures that DNA is copied exactly once per cell division.

Beyond its role in replication, the ORC6 protein is involved in the structure of heterochromatin (densely packed DNA) and plays a role in cytokinesis, the process by which dividing cells physically separate from one another.

Health Conditions Related to Genetic Changes

Meier-Gorlin syndrome

Mutations in the ORC6 gene have been identified as a cause of Meier-Gorlin syndrome, a condition characterized by short stature, small ears, and underdeveloped kneecaps. Known mutations include:

  • Tyr232Ser: A substitution of the amino acid serine for tyrosine at position 232.
  • Truncation: Mutations that lead to the production of an abnormally short protein.

These genetic changes impair the assembly of the pre-replication complex, which disrupts replication licensing. Researchers believe this disruption delays the cell division process, thereby slowing the growth of bones and other tissues during development. Some evidence also suggests that ORC6 alterations may impair cytokinesis, further contributing to delayed cell division, though the specific reasons why ear and kneecap development are disproportionately affected remain unknown.

Frequently Asked Questions

Meier-Gorlin syndrome, when caused by mutations in the ORC6 gene, is primarily characterized by short stature, microtia (small or underdeveloped ears), and hypoplasia of the patella (underdeveloped kneecaps). These features result from disrupted DNA replication licensing and impaired cytokinesis, which slow down cell division during fetal development. The delay in cell division affects the growth of bones and other tissues, leading to the distinctive physical traits observed in affected individuals. How do ORC6 mutations disrupt the normal process of cell division?::ORC6 is a subunit of the origin recognition complex (ORC), which is essential for initiating DNA replication. Mutations in ORC6, such as the Tyr232Ser substitution or truncating mutations, impair the assembly of the pre-replication complex. This disruption prevents proper replication licensing, ensuring that DNA is not copied correctly or at the right time. Additionally, ORC6 alterations may affect cytokinesis, the final stage of cell division where the cell physically splits. The combined effect of delayed replication and impaired cytokinesis slows overall cell division, leading to the growth deficiencies seen in Meier-Gorlin syndrome. Is Meier-Gorlin syndrome caused by ORC6 mutations inherited in a specific pattern?::Meier-Gorlin syndrome caused by ORC6 mutations is typically inherited in an autosomal recessive pattern. This means that an individual must inherit two mutated copies of the ORC6 gene, one from each parent, to develop the condition. Parents who carry one mutated copy are usually asymptomatic carriers. Because the condition is recessive, it can occur in siblings of an affected child, and there is a 25% chance of recurrence in future pregnancies if both parents are carriers. Are there any known treatments or management strategies for Meier-Gorlin syndrome related to ORC6?::There is currently no cure for Meier-Gorlin syndrome, and treatment is primarily supportive and aimed at managing specific symptoms. Management may include orthopedic interventions for skeletal abnormalities, such as patellar hypoplasia, and audiological support if hearing issues are present due to ear malformations. Growth hormone therapy has been explored in some cases to address short stature, but its efficacy can vary. Regular monitoring by a multidisciplinary team, including geneticists, orthopedists, and audiologists, is recommended to address developmental and physical challenges as the individual grows.
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.