Chromosome 18p duplication

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Other Names:

Duplication 18p; Trisomy 18p; 18p duplication; Duplication 18p; Trisomy 18p; 18p duplication; 18p trisomy; Partial trisomy 18p See More

Categories:

Congenital and Genetic Diseases

Summary Summary

Chromosome 18p duplication is a rare chromosome abnormality in which there are three copies of the short (p) arm of chromosome 18 in each cell, rather than the usual two copies. The severity of the condition and the signs and symptoms depend on the size and location of the duplicated genetic material and which genes are involved.^[1]^[2] A complete duplication of the p arm of chromosome 18 is rare.^[3] Reported features include: intellectual disability, foot or hand anomalies, distinctive facial features, and epilepsy.^[1]^[2]^[3]^[4] Chromosome 18p duplication may occur sporadically in a family with no previous history or may be inherited from a parent with the same duplication or another chromosome abnormality, such as a balanced translocation.^[4] Treatment is based on the signs and symptoms present in each person.^[1]^[2]^[3]

Last updated: 10/27/2016

Symptoms Symptoms

The severity of chromosome 18p duplication and the signs and symptoms present depend on the size and location of the duplicated genetic material and which genes are involved. Features commonly include: intellectual disability that ranges from mild to severe, characteristic facial features, and epilepsy. Other findings reported in the medical literature include: hand and foot anomalies, decreased muscle tone (hypotonia), and developmental delay.^[1]^[2]^[5]^[3]^[4]

Some researchers have suggested that several of the cases reported in the medical literature may represent cases in which other chromosome changes are present but are not yet identified. This may help explain the variability in the signs and symptoms present.^[2]^[5] It is additionally suspected that some individuals with chromosome 18p duplication may not be diagnosed if they have mild or absent signs and symptoms and are of normal intelligence.^[2]

Last updated: 10/27/2016

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 the pinna	Abnormally shaped ears Auricular malformation Deformed ears Malformed ears [ more ]	0000377
Attention deficit hyperactivity disorder	Attention deficit Attention deficit disorder Attention deficit-hyperactivity disorder Attention deficits Childhood attention deficit/hyperactivity disorder [ more ]	0007018
Bilateral cryptorchidism		0008689
Blepharophimosis	Narrow opening between the eyelids	0000581
Highly arched eyebrow	Arched eyebrows Broad, arched eyebrows High, rounded eyebrows High-arched eyebrows Thick, flared eyebrows [ more ]	0002553
Hypotelorism	Abnormally close eyes Closely spaced eyes [ more ]	0000601
Intellectual disability, mild	Mental retardation, borderline-mild Mild and nonprogressive mental retardation Mild mental retardation [ more ]	0001256
Midface retrusion	Decreased size of midface Midface deficiency Underdevelopment of midface [ more ]	0011800
Polyphagia	Voracious appetite	0002591
Preauricular skin tag		0000384
Pyloric stenosis		0002021
Sloping forehead	Inclined forehead Receding forehead [ more ]	0000340
Telecanthus	Corners of eye widely separated	0000506
Thin vermilion border	Decreased volume of lip Thin lips [ more ]	0000233
Underdeveloped nasal alae	Underdeveloped tissue around nostril	0000430
Upslanted palpebral fissure	Upward slanting of the opening between the eyelids	0000582
Wide nasal bridge	Broad nasal bridge Broad nasal root Broadened nasal bridge Increased breadth of bridge of nose Increased breadth of nasal bridge Increased width of bridge of nose Increased width of nasal bridge Nasal bridge broad Wide bridge of nose Widened nasal bridge [ more ]	0000431
30%-79% of people have these symptoms
Abnormal foot morphology	Abnormal feet structure Abnormality of the feet Abnormality of the foot Foot deformities Foot deformity [ more ]	0001760
Abnormality of finger	Abnormalities of the fingers	0001167
Narrow mouth	Small mouth	0000160
5%-29% of people have these symptoms
Abnormality of cardiovascular system morphology		0030680
Facial palsy	Bell's palsy	0010628
High, narrow palate	Narrow, high-arched roof of mouth Narrow, highly arched roof of mouth [ more ]	0002705
Intrauterine growth retardation	Prenatal growth deficiency Prenatal growth retardation [ more ]	0001511
Microcephaly	Abnormally small skull Decreased circumference of cranium Decreased size of skull Reduced head circumference Small head circumference [ more ]	0000252
Micrognathia	Little lower jaw Small jaw Small lower jaw [ more ]	0000347
Neonatal hypotonia	Low muscle tone, in neonatal onset	0001319
Short stature	Decreased body height Small stature [ more ]	0004322

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Do you have more information about symptoms of this disease? We want to hear from you.

Last updated: 2/1/2021

Do you have updated information on this disease? We want to hear from you.

Treatment Treatment

Because the presence and severity of signs and symptoms vary from person to person, treatment also varies. If an intellectual disability and/or developmental delay is present, early educational intervention and early services are important.

It is essential to work with one's person's health care provider and medical team to determine the appropriate medical management plan.

Last updated: 10/27/2016

Research Research

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 duplication. 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 duplication:
Chromosome 18 Registry & Research Society

Organizations Organizations

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

Chromosome Disorder Outreach (CDO)
PO Box 724
Boca Raton, FL 33429
Telephone: +1-561-395-4252
E-mail: https://chromodisorder.org/contact/
Website: https://chromodisorder.org/
Hope For Trisomy
PO Box 121986
Arlington, TX 76012
Toll-free: 1-866-977-6637
E-mail: staff@hopefortrisomy13and18.org
Website: https://www.hopefortrisomy13and18.org/
Support Organization for Trisomy 18, 13, and Related Disorders (SOFT)
c/o Barb Vanherreweghe
2982 South Union Street
Rochester, NY 14624
Toll-free: 800-716-SOFT (7638)
Telephone: 585-594-4621
E-mail: barbsoft@rochester.rr.com
Website: https://trisomy.org/
Trisomy 18 Foundation
4491 Cheshire Station Plaza
Suite 157
Dale City, VA 22193
Telephone: +1-810-867-4211
E-mail: t18info@trisomy18.org
Website: https://www.trisomy18.org/
Unique – Rare Chromosome Disorder Support Group
G1, The Stables
Station Road West
Surrey
RH8 9EE
United Kingdom
Telephone: +44 (0)1883 723356
E-mail: info@rarechromo.org
Website: https://www.rarechromo.org/

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Learn More 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 Human Genome Research Institute, part of the National Institutes of Health (NIH), has developed a fact sheet on chromosome abnormalities, which may be helpful to you. To read this information, visit the link.

MedlinePlus, the National Library of Medicine Web site designed to direct you to information and resources that help you research your health questions, provides further information about chromosomes. Click on the link.
Genetics Home Reference (GHR) contains information on Chromosome 18p duplication. This website is maintained by the National Library of Medicine.

In-Depth Information

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 duplication. Click on the link to view a sample search on this topic.

News & Events News & Events

News

Rare Disease Day at NIH 2021
March 1, 2021

GARD Answers GARD Answers

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. Submit a new question

What are some of the signs or symptoms associated with trisomy 18p? What are some of the behavioural characteristics of this syndrome if any? What are some treatment options for an adolescent with this syndrome, ASD (autism spectrum disorder), and no intellectual disability displaying challenging behaviours? See answer

Have a question? Contact a GARD Information Specialist.

References References

Rodríguez L, Liehr T, Mrasek K, Mansilla E, Martínez-Fernández ML, Garcia A, Martínez-Frías ML. Small Supernumerary Chromosome Marker Generating Complete and Pure Trisomy 18p, Characterized by Molecular Cytogenetic Techniques and Review. American Journal of Medical Genetics Part A. 2007; 143A(22):2727-2732. https://www.ncbi.nlm.nih.gov/pubmed/17937429.
Mabboux P, Brisset S, Aboura A, Pineau D, Kourbi V, Joannidis S et al. Pure and Complete Trisomy 18p Due to a Supernumerary Marker Chromosome Associated with Moderate Mental Retardation. American Journal of Medical Genetics Part A. 2007; 143A(7):727-733. https://www.ncbi.nlm.nih.gov/pubmed/17330860.
Azoospermia and trisomy 18p syndrome: a fortuitous association? A patient report and a review of the literature. Guillaume Jedraszak, Henri Copin, Manuel Demailly, Catherine Quibel, Thierry Leclerc, Marlène Gallet, Moncef Benkhalifa, Aline Receveur. Molecular cytogenetics. June 4. 2015; 8(34):https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4453045/.
Orendi K, Uhrig S, Mach M, Tschepper P, Speicher MR. Complete and pure trisomy 18p due to a complex chromosomal rearrangement in a male adult with mild intellectual disability.. American Journal of Medical Genetics (Part A). May 21, 2013; 161A(7):1806-1812. https://www.ncbi.nlm.nih.gov/pubmed/23695988.
Schinzel A. Catalogue of Unbalanced Chromosome Aberrations in Man. New York: Walter de Gruyter; 2001;