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 12p duplication



Other Names:
Duplication 12p; Trisomy 12p; 12p duplication; Duplication 12p; Trisomy 12p; 12p duplication; 12p trisomy; Partial trisomy 12p See More
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Chromosome 12p duplication is a chromosome abnormality that occurs when there is an extra copy of genetic material on the short arm (p) of chromosome 12. The severity of the condition and the signs and symptoms depend on the size and location of the duplication and which genes are involved. Features that often occur in people with chromosome 12p duplication include macrocephaly (unusually large head), abnormal muscle tone, characteristic facial features, developmental delay and intellectual disability.[1] Most cases are not inherited, but people can pass the duplication on to their children. Treatment is based on the signs and symptoms present in each person.
Last updated: 12/16/2015

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 chromosome segregation 0002916
Abnormality of the antihelix 0009738
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
0004209
Downturned corners of mouth
Downturned corners of the mouth
Downturned mouth
[ more ]
0002714
Epicanthus
Eye folds
Prominent eye folds
[ more ]
0000286
Everted lower lip vermilion
Drooping lower lip
Outward turned lower lip
[ more ]
0000232
Flat face
Flat facial shape
0012368
Full cheeks
Apple cheeks
Big cheeks
Increased size of cheeks
Large cheeks
[ more ]
0000293
Global developmental delay 0001263
Hypertelorism
Wide-set eyes
Widely spaced eyes
[ more ]
0000316
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ]
0001249
Large hands
large hand
0001176
Malar flattening
Zygomatic flattening
0000272
Micrognathia
Little lower jaw
Small jaw
Small lower jaw
[ more ]
0000347
Short neck
Decreased length of neck
0000470
Short nose
Decreased length of nose
Shortened nose
[ more ]
0003196
Thick eyebrow
Bushy eyebrows
Dense eyebrow
Heavy eyebrows
Prominent eyebrows
Thick eyebrows
[ more ]
0000574
Thickened nuchal skin fold
Thickened skin folds of neck
Thickened skin over the neck
[ more ]
0000474
Turricephaly
Tall shaped skull
Tower skull shape
[ more ]
0000262
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
Abnormality of cardiovascular system morphology 0030680
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development
[ more ]
0002750
Low-set ears
Low set ears
Lowset ears
[ more ]
0000369
Proptosis
Bulging eye
Eyeballs bulging out
Prominent eyes
Prominent globes
Protruding eyes
[ more ]
0000520
Short stature
Decreased body height
Small stature
[ more ]
0004322
5%-29% of people have these symptoms
Abnormality of the urinary system
Urinary tract abnormalities
Urinary tract abnormality
Urinary tract anomalies
[ more ]
0000079
Anal atresia
Absent anus
0002023
Aplasia/Hypoplasia of the iris
Absent/small iris
Absent/underdeveloped iris
[ more ]
0008053
Cleft palate
Cleft roof of mouth
0000175
Supernumerary nipple
Accessory nipple
0002558
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Last updated: 7/1/2020

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 12p duplication. This website is maintained by the National Library of Medicine.
  • 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 duplications of 12p.

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 12p duplication. Click on the link to view a sample search on this topic.

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  1. Bianchi D and Hulten M. Duplications of 12p. Unique. 2007; http://www.rarechromo.org/information/Chromosome%2012/Duplications%20of%2012p%20FTNW.pdf.