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ORC1 gene

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

ORC1 gene

The ORC1 gene is critical for DNA replication and cell division, and mutations in this gene are associated with Meier-Gorlin syndrome.

Normal Function

The ORC1 gene provides instructions for making a protein that is a key component of the origin recognition complex (ORC). This complex is essential for DNA replication, the process of copying a cell's DNA before it divides. The ORC attaches to specific DNA regions called origins of replication, where it helps form a pre-replication complex. This process, known as replication licensing, ensures that DNA is copied only once per cell division.

Beyond its role in replication, the ORC1 protein performs several other functions:

  • Heterochromatin Binding: It attaches to heterochromatin, which is densely packed DNA involved in maintaining chromosome structure and controlling gene activity.
  • Centrosome Regulation: It helps regulate the copying of centrosomes and centrioles, ensuring they are not copied more than once, which is vital for normal cell division.
  • Cilia Function: Research suggests ORC1 is involved in the function of cilia, microscopic projections on cell surfaces that participate in signaling pathways important for the development of tissues, including bone.

Health Conditions Related to Genetic Changes

Meier-Gorlin syndrome

Mutations in the ORC1 gene cause Meier-Gorlin syndrome, a condition characterized by short stature, small ears, and underdeveloped kneecaps. These mutations typically alter the ORC1 protein or lead to the production of an abnormally short version.

While the exact mechanism is not fully understood, researchers believe these mutations impair the assembly of the pre-replication complex, which may delay cell division and slow the growth of bones and tissues. Additionally, alterations in ORC1 may lead to an incorrect number of centrosomes or impair cilia function, both of which may contribute to the developmental abnormalities seen in this syndrome.

Other Names for This Gene

  • HSORC1
  • ORC1_HUMAN
  • ORC1L
  • origin recognition complex, subunit 1
  • origin recognition complex, subunit 1 homolog
  • PARC1
  • replication control protein 1

Frequently Asked Questions

Meier‑Gorlin syndrome caused by ORC1 mutations follows an autosomal‑recessive pattern. Both parents are typically carriers of one altered copy of the gene but are unaffected. 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. Genetic counseling and carrier testing for the parents are recommended before future pregnancies.
clinical diagnostic test usually involves targeted next‑generation sequencing (NGS) of a panel that includes ORC1, or whole‑exome sequencing if the phenotype is unclear. Blood is the most common specimen; a cheek swab can be used for some labs. No special preparation is required, but you should provide a detailed family and medical history to help the laboratory interpret variants.
Growth hormone therapy has been tried in some children with Meier‑Gorlin syndrome, but evidence of benefit is limited and response varies. Orthopedic monitoring is essential; physiotherapy and, in selected cases, surgical reconstruction of the patella can improve knee function. Management should be individualized by a multidisciplinary team including endocrinology, genetics, and orthopedics.
Routine surveillance focuses on growth, dental development, and orthopedic assessment. Because ORC1 participates in DNA replication, there is currently no proven increased cancer risk, but standard age‑appropriate cancer screenings are advised. Monitoring for respiratory infections and hearing loss is also recommended, as ear anomalies can predispose to middle‑ear problems.
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.