Rare Gastroenterology News

Disease Profile

Ring chromosome 18

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
<1 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Chromosome 18 ring; Ring 18; R18


Chromosome Disorders; Congenital and Genetic Diseases


Ring chromosome 18 is a rare chromosome abnormality in which the ends (arms) of chromosome 18 join together to form a ring shape. When a ring chromosome forms, genetic material can be lost from either arm or both arms, causing various signs and symptoms. While most people with ring chromosome 18 have the ring chromosome in all of their body cells, some people also have some body cells with normal chromosomes (this is called mosaicism). People with ring chromosome 18 mosaicism may have milder symptoms.[1]

Depending on the amount of genetic material lost and which genes are involved, signs and symptoms that may be present in a person with ring chromosome 18 include ear and hearing abnormalities, abnormally-developed feet or hands, genital abnormalities in males, an increased risk to develop juvenile rheumatoid arthritis, holoprosencephaly, developmental delays, learning difficulties, short stature, and/or various birth defects.[1]

Ring chromosome 18 usually occurs sporadically (by chance) during the formation of egg or sperm cells or shortly after the egg and sperm join together. Occasionally, it is inherited from a parent (typically the mother).[1] A chromosome test of the parents can help determine whether it was inherited and whether future children have an increased chance to have a chromosome abnormality. Treatment for ring chromosome 18 depends on the signs and symptoms present in each person.


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
    • Unique is a source of information and support to families and individuals affected by rare chromosome disorders. Click on the link to view information about ring chromosome 18.

      In-Depth Information

      • The Chromosome 18 Clinical Research Center provides clinical management guidelines for people with different disorders involving chromosome 18, including Ring chromosome 18.
      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Ring chromosome 18. Click on the link to view a sample search on this topic.