National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Isodicentric chromosome 15 syndrome


Other Names:
Duplication/inversion 15q11; Inv dup(15); Non-distal tetrasomy 15q; Duplication/inversion 15q11; Inv dup(15); Non-distal tetrasomy 15q; Non-telomeric tetrasomy 15q; Idic(15); Tetrasomy 15q; Chromosome 15q tetrasomy; Inverted duplication 15 See More
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This disease is grouped under:
Isodicentric chromosome 15 syndrome is a chromosome abnormality that affects many different parts of the body. As the name suggests, people with this condition have an extra chromosome (called an isodicentric chromosome 15) which is made of two pieces of chromosome 15 that are stuck together end-to-end. Although the severity of the condition and the associated features vary from person to person, common signs and symptoms include poor muscle tone in newborns; developmental delay; mild to severe intellectual disability; delayed or absent speech; behavioral abnormalities; and seizures.[1][2] Most cases of isodicentric chromosome 15 syndrome occur sporadically in people with no family history of the condition.[3][1] Treatment is based on the signs and symptoms present in each person.[1]
Last updated: 1/21/2016

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
Autistic behavior 0000729
Drooling
Dribbling
0002307
Generalized hypotonia
Decreased muscle tone
Low muscle tone
[ more ] 		0001290
Joint hypermobility
Double-Jointed
Flexible joints
Increased mobility of joints
[ more ] 		0001382
30%-79% of people have these symptoms
Echolalia
Echoing another person's speech
0010529
Feeding difficulties
Feeding problems
Poor feeding
[ more ] 		0011968
Hyperactivity
More active than typical
0000752
Seizure 0001250
Self-biting 0012169
Severe expressive language delay 0006863
Severe receptive language delay 0011352
Stereotypy
Repetitive movements
Repetitive or self-injurious behavior
[ more ] 		0000733
5%-29% of people have these symptoms
2-3 toe syndactyly
Webbed 2nd and 3rd toes
0004691
Abnormal facial shape
Unusual facial appearance
0001999
Aggressive behavior
Aggression
Aggressive behaviour
Aggressiveness
[ more ] 		0000718
Brachycephaly
Short and broad skull
0000248
Brachydactyly
Short fingers or toes
0001156
Broad nasal tip
Broad tip of nose
Broad, upturned nose
Increased breadth of nasal tip
Increased breadth of tip of nose
Increased width of nasal tip
Increased width of tip of nose
Nasal tip, broad
Nasal tip, wide
Wide tip of nose
[ more ] 		0000455
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
0004209
Deeply set eye
Deep set eye
Deep-set eyes
Sunken eye
[ more ] 		0000490
Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
0000494
Epicanthus
Eye folds
Prominent eye folds
[ more ] 		0000286
Growth delay
Delayed growth
Growth deficiency
Growth failure
Growth retardation
Poor growth
Retarded growth
[ more ] 		0001510
High palate
Elevated palate
Increased palatal height
[ more ] 		0000218
Hypogonadism
Decreased activity of gonads
0000135
Low-set, posteriorly rotated ears 0000368
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference
[ more ] 		0000252
Short philtrum 0000322
Strabismus
Cross-eyed
Squint
Squint eyes
[ more ] 		0000486
Synophrys
Monobrow
Unibrow
[ more ] 		0000664
1%-4% of people have these symptoms
Cryptorchidism
Undescended testes
Undescended testis
[ more ] 		0000028
Gonadal dysgenesis 0000133
Hernia 0100790
Precocious puberty
Early onset of puberty
Early puberty
[ more ] 		0000826
Talipes equinovarus
Club feet
Club foot
Clubfeet
Clubfoot
[ more ] 		0001762
Tetralogy of Fallot 0001636
Unilateral renal agenesis
Absent kidney on one side
Missing one kidney
Single kidney
[ more ] 		0000122
Ventricular septal defect
Hole in heart wall separating two lower heart chambers
0001629
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Last updated: 7/1/2020

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
The possible occurrence of double supernumerary isodicentric chromosomes derived from chromosome 15, resulting in partial hexasomy of the maternally inherited PWS/ASCR, should be considered in the differential diagnosis.
Visit the Orphanet disease page for more information.

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 Isodicentric chromosome 15 syndrome. This website is maintained by the National Library of Medicine.
  • Unique is a source of information and support for families and individuals affected by rare chromosome disorders. Click on the link to view information about Isodicentric chromosome 15 syndrome.

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 Isodicentric chromosome 15 syndrome. Click on the link to view a sample search on this topic.

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  1. Idic(15). Unique. 2014; http://www.rarechromo.org/information/Chromosome%2015/Idic%2815%29%20FTNW.pdf.
  2. Rim JH, Chung HJ, Shin S, Park SJ, Choi JR. Isodicentric Chromosome 15 Syndrome in a Korean Patient With Café-au-lait Spots. Ann Lab Med. July 2015; 35(4):474-476.
  3. Isodicentric chromosome 15 syndrome. Genetics Home Reference. September 2012; http://ghr.nlm.nih.gov/condition/isodicentric-chromosome-15-syndrome.