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Disease Profile

1q21.1 microdeletion syndrome

Prevalence
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.

Unknown

US Estimated

Europe Estimated

Age of onset

Infancy

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ICD-10

Q93.5

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.

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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.

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X-linked
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.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.

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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.

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Not applicable

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Other names (AKA)

Chromosome 1q21.1 microdeletion syndrome; 1q21.1 microdeletion; Monosomy 1q21.1

Categories

Chromosome Disorders; Congenital and Genetic Diseases

Summary

1q21.1 microdeletion syndrome is a chromosome abnormality where a segment of genetic material on the long arm (or q arm) of chromosome 1 at position 21.1 is missing (or deleted). Some people with this deletion have no observable features while others have variable findings that can include a small head (microcephaly), developmental delay (speech and motor delays), mild intellectual disability, distinctive facial features, and eye abnormalities. Other findings can include seizures as well as abnormalities of the heart, skeleton, and urinary system. Psychiatric and behavioral features can include autism spectrum disorders, anxiety and mood disorders, schizophrenia, attention deficit hyperactivity disorder and sleep disorders. This syndrome is caused by a deletion in a specific region of 1q21.1, which is distinct from the deletion region that causes TAR syndrome.[1][2][3]

Symptoms

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.

Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Bulbous nose
0000414
Deeply set eye
Deep set eye
Deep-set eyes
Sunken eye

[ more ]

 0000490
Epicanthus
Eye folds
Prominent eye folds

[ more ]

 0000286
Frontal bossing
0002007
Global developmental delay
0001263
High palate
Elevated palate
Increased palatal height

[ more ]

 0000218
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

 0001249
Long philtrum
0000343
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

 0000252
Short stature
Decreased body height
Small stature

[ more ]

 0004322
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
5%-29% of people have these symptoms
Abnormal cardiac septum morphology
0001671
Agenesis of corpus callosum
0001274
Ankyloglossia
Tongue tied
0010296
Anxiety
Excessive, persistent worry and fear
0000739
Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder

[ more ]

 0007018
Autism
0000717
Broad hallux phalanx
Broad bone of big toe
Wide bone of big toe

[ more ]

 0010059
Broad thumb
Broad thumbs
Wide/broad thumb

[ more ]

 0011304
Cataract
Clouding of the lens of the eye
Cloudy lens

[ more ]

 0000518
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
0004209
Cryptorchidism
Undescended testes
Undescended testis

[ more ]

 0000028
Depressivity
Depression
0000716
Failure to thrive
Faltering weight
Weight faltering

[ more ]

 0001508
Foot polydactyly
Duplication of bones of the toes
0001829
Hand polydactyly
Extra finger
0001161
High hypermetropia
Severe farsightedness
Severe long-sightedness

[ more ]

 0008499
Hydrocephalus
Too much cerebrospinal fluid in the brain
0000238
Hydronephrosis
0000126
Inguinal hernia
0000023
Interrupted aortic arch
0011611
Intrauterine growth retardation
Prenatal growth deficiency
Prenatal growth retardation

[ more ]

 0001511
Iris coloboma
Cat eye
0000612
Joint hyperflexibility
Joints move beyond expected range of motion
0005692
Microphthalmia
Abnormally small eyeball
0000568
Muscular hypotonia
Low or weak muscle tone
0001252
Patent ductus arteriosus
0001643
Schizophrenia
0100753
Scoliosis
0002650
Seizure
0001250
Sensorineural hearing impairment
0000407
Short foot
Short feet
Small feet

[ more ]

 0001773
Sleep disturbance
Difficulty sleeping
Trouble sleeping

[ more ]

 0002360
Strabismus
Cross-eyed
Squint
Squint eyes

[ more ]

 0000486
Talipes equinovarus
Club feet
Club foot
Clubfeet
Clubfoot

[ more ]

 0001762
Toe syndactyly
Fused toes
Webbed toes

[ more ]

 0001770
Vesicoureteral reflux
0000076
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
0000006
Bicuspid aortic valve
Aortic valve has two leaflets rather than three
0001647
Broad hallux
Broad big toe
Wide big toe

[ more ]

 0010055
Coarctation of aorta
Narrowing of aorta
Narrowing of the aorta

[ more ]

 0001680
Incomplete penetrance
0003829
Sporadic
No previous family history
0003745
Transposition of the great arteries
0001669
Truncus arteriosus

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

    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 1q21.1 microdeletion 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 microdeletion syndrome.

      In-Depth Information

      • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
      • 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.

        References

        1. 1q21.1 microdeletion syndrome. Orphanet. March 2011; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=250989.
        2. Haldeman-Englert C & Jewett T. 1q21.1 Recurrent Microdeletion. GeneReviews. November 12, 2015; https://www.ncbi.nlm.nih.gov/books/NBK52787.
        3. Mefford H, Hulten M. 1q21 microdeletions. Unique. 2014; https://www.rarechromo.org/information/Chromosome%20%201/1q21.1%20microdeletions%20FTNW.pdf.

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