National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Chromosome 18p tetrasomy


Other Names:
Tetrasomy 18p; Tetrasomy chromosome 18p; Isochromosome 18p
Categories:
Chromosome 18p tetrasomy is a chromosomal disorder that affects many parts of the body. It occurs when the short arm of chromosome 18 (18p) appears four times (tetrasomy) rather than the normal two times in cells of the body.[1][2] The symptoms of chromosomy 18p tetrasomy vary from case to case but may include abnormalities of the head and face (craniofacial) area, malformations of the spine, hands, and/or feet, neuromuscular abnormalities, kidney malformations, intellectual disability, speech delays, and behavioral abnormalities. In most cases, chromosome 18p tetrasomy is the result of a spontaneous (de novo) genetic change (mutation) early in fetal development during pregnancy. Although there is no specific treatment or cure for chromosome 18p tetrasomy, there are ways to manage the symptoms. A team of doctors or specialists is often needed to figure out the treatment options for each person.[1][3]
Last updated: 7/25/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of neuronal migration 0002269
Long philtrum 0000343
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference
[ more ] 		0000252
30%-79% of people have these symptoms
Epicanthus
Eye folds
Prominent eye folds
[ more ] 		0000286
Low-set, posteriorly rotated ears 0000368
5%-29% of people have these symptoms
Achalasia 0002571
Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
0000494
Facial asymmetry
Asymmetry of face
Crooked face
Unsymmetrical face
[ more ] 		0000324
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait
[ more ] 		0001288
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Large hands
large hand
0001176
Narrow mouth
Small mouth
0000160
Scoliosis 0002650
Seizure 0001250
Short nose
Decreased length of nose
Shortened nose
[ more ] 		0003196
Syncope
Fainting spell
0001279
Thin vermilion border
Decreased volume of lip
Thin lips
[ more ] 		0000233
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Last updated: 7/1/2020

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Chromosome 18p tetrasomy. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Chromosome 18p tetrasomy:
    Chromosome 18 Registry & Research Society
     

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

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

  • Genetics Home Reference (GHR) contains information on Chromosome 18p tetrasomy. This website is maintained by the National Library of Medicine.
  • 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.

In-Depth Information

  • The Chromosome 18 Clinical Research Center provides clinical management guidelines for people with different disorders involving chromosome 18, including Chromosome 18p tetrasomy.
  • 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 Chromosome 18p tetrasomy. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Chromosome 18, Tetrasomy 18p. National Organization for Rare Disorders (NORD). 2009; http://rarediseases.org/rare-diseases/chromosome-18-tetrasomy-18p/.
  2. Tetrasomy 18p. Chromosome 18 Registry and Research Society. 12/9/2015; http://www.chromosome18.org/tetrasomy-18p/.
  3. Courtney Sebold, Elizabeth Roeder, Marsha Zimmerman, Bridgette Soileau, Patricia Heard,1 Erika Carter, Martha Schatz, W. Abraham White, Brian Perry, Kent Reinker, Louise O’Donnell, Jack Lancaster, John Li, Minire Hasi, Annice Hill, Lauren Pankratz, Daniel E. Hale, Jannine D. Cody. Tetrasomy 18p: Report of the Molecular and Clinical Findings of 43 Individuals. American Journal of Medical Genetics. June 2010; 152A:2164-2172. http://www.ncbi.nlm.nih.gov/pubmed/20803640.