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 1q21.1 duplication syndrome


Other Names:
1q21.1 microduplication syndrome
Categories:
This disease is grouped under:
Chromosome 1q21.1 duplication syndrome is a rare condition caused by the presence of an extra copy of a small piece of chromosome 1 in the cells of the body. Signs and symptoms can vary widely among affected individuals. Some individuals have no symptoms, while others may have features such as a large head size (macrocephaly); mild to moderate developmental delay and learning difficulties; autism or autistic-like behavior; heart problems; seizures; and/or and distinctive facial features.[1][2] This condition can occur sporadically as a de novo mutation (by chance) or can be inherited in an autosomal dominant manner from a parent. Treatment depends on the signs and symptoms present in each individual.
Last updated: 8/15/2013

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
Global developmental delay 0001263
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
30%-79% of people have these symptoms
Frontal bossing 0002007
Hypertelorism
Wide-set eyes
Widely spaced eyes
[ more ] 		0000316
Macrocephaly
Increased size of skull
Large head
Large head circumference
[ more ] 		0000256
5%-29% of people have these symptoms
Arthrogryposis multiplex congenita 0002804
Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder
[ more ] 		0007018
Autism 0000717
Cataract
Clouding of the lens of the eye
Cloudy lens
[ more ] 		0000518
Cryptorchidism
Undescended testes
Undescended testis
[ more ] 		0000028
Failure to thrive
Faltering weight
Weight faltering
[ more ] 		0001508
Gastroesophageal reflux
Acid reflux
Acid reflux disease
Heartburn
[ more ] 		0002020
Glaucoma 0000501
Hallucinations
Hallucination
Sensory hallucination
[ more ] 		0000738
Hip dislocation
Dislocated hips
Dislocation of hip
[ more ] 		0002827
Hip dysplasia 0001385
Hydrocephalus
Too much cerebrospinal fluid in the brain
0000238
Hypertonia 0001276
Hypospadias 0000047
Intellectual disability, mild
Mental retardation, borderline-mild
Mild and nonprogressive mental retardation
Mild mental retardation
[ more ] 		0001256
Muscular hypotonia
Low or weak muscle tone
0001252
Schizophrenia 0100753
Seizure 0001250
Strabismus
Cross-eyed
Squint
Squint eyes
[ more ] 		0000486
Talipes equinovarus
Club feet
Club foot
Clubfeet
Clubfoot
[ more ] 		0001762
Tetralogy of Fallot 0001636
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Hypoplasia of the corpus callosum
Underdevelopment of part of brain called corpus callosum
0002079
Incomplete penetrance 0003829
Specific learning disability 0001328
Sporadic
No previous family history
0003745
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Last updated: 7/1/2020
Chromosome 1q21.1 duplication syndrome can occur sporadically (by chance) from a de novo mutation or can be inherited in an autosomal dominant manner from a parent that has the same duplication. When the condition occurs sporadically, it is caused by a random error during the formation of the egg or sperm cell, or during the early days after fertilization.[2] The duplication occurs when part of chromosome 1 is copied (duplicated) abnormally, resulting in the extra genetic material from the duplicated segment.[3] If the condition is inherited from a parent, it means that one of the parents also has the extra piece of genetic material. In these cases, the parent with the duplication has a 50% chance with each pregnancy to pass the duplication on to his/her child. The only way to know if it has been inherited from a parent is for the parents to have genetic testing. A parent with the duplication may not have any signs or symptoms. In both cases, nothing that either parent does, or does not do, can cause this syndrome to occur.

Individuals who are interested in genetic testing for themselves or family members should speak with a genetics professional.
Last updated: 8/15/2013

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

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 1q21.1 duplication syndrome. 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 1q21.1 duplication syndrome:
    Simons SearchLight
     

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 1q21.1 duplication syndrome. 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 1q21.1 microduplications.

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.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • 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 1q21.1 duplication syndrome. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

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. Hamoush A. Chromosome 1q21.1 duplication syndrome. OMIM. June 10, 2009; http://www.ncbi.nlm.nih.gov/omim/612475. Accessed 11/4/2010.
  2. 1q21.1 Microduplications. Unique. June 2011; http://www.rarechromo.org/information/Chromosome%20%201/1q21.1%20microduplications%20FTNW.pdf. Accessed 8/15/2013.
  3. Chromosomal duplication. Genetics Home Reference. August 12, 2013; http://ghr.nlm.nih.gov/handbook/illustrations/chromosomalduplication. Accessed 8/15/2013.