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Disease Profile

Chromosome 20p duplication

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

US Estimated

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)

Duplication 20p; Trisomy 20p; 20p duplication;


Chromosome Disorders


Chromosome 20p duplication is a rare chromosome abnormality that occurs when there is an extra copy (duplication) of genetic material on the short arm (p) of chromosome 20. The severity of the condition and the signs and symptoms depend on the size and location of the duplication and which genes are involved. In general, smaller duplications are less severe than larger duplications.[1]

Very few cases of chromosome 20p duplication have been reported. The majority of those have been partial duplications (involving only part of the p arm) and have occurred as part of a translocation (along with a deletion on another chromosome).[2] Therefore, it is hard to know which symptoms in people with a 20p duplication have been due to the duplication specifically. Signs and symptoms that have been reported in people with chromosome 20p duplication include intellectual disability, developmental delay, speech delay, poor coordination, dental problems, spinal bone abnormalities, distinctive facial features, and heart problems.[1][2]

Most cases of chromosome 20p duplication have resulted from a healthy parent having a chromosomal balanced translocation or inversion (when a piece of a chromosome is facing the wrong direction).[2] When a parent has one of these, there is an increased risk to have another child with a chromosome abnormality. Some chromosome 20p duplications have resulted from a random genetic error (not inherited), in which both parents have normal chromosomes. In these cases, it is unlikely the parents would have another child with a chromosome abnormality.[1]

Treatment for chromosome 20p duplications 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

    • Genetics Home Reference (GHR) contains information on Chromosome 20p 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 20p.

      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.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Chromosome 20p duplication. Click on the link to view a sample search on this topic.


        1. Duplications of 20p. Unique. 2007; https://www.rarechromo.org/information/Chromosome%2020/20p%20duplications%20FTNW.pdf.
        2. Bartolini L, Sartori S, Lenzini E et al. De novo trisomy 20p characterized by array comparative genomic hybridization: report of a novel case and review of the literature. Gene. July 25, 2013; 524(2):368-372. https://www.ncbi.nlm.nih.gov/pubmed/23612255.