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ORPHA:870Malformation syndrome
Also called Trisomy 21
What it is
A total autosomal trisomy that is caused by the presence of a third (partial or total) copy of chromosome 21 and that is characterized by variable intellectual disability, muscular hypotonia, and joint laxity, often associated with a characteristic facial dysmorphism and various anomalies such as cardiac, gastrointestinal, neurosensorial or endocrine defects.
Key facts
- Prevalence
- 1-5 / 10 000
- Age of onset
- Antenatal, Neonatal
- Inheritance
- Not applicable
- Classified as
- Malformation syndrome
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
14Common30–79%
32- Abnormal cardiovascular system morphology
- Abnormality of blood and blood-forming tissues
- Abnormality of immune system physiology
- Abnormality of the dentition
- Abnormality of the fontanelles or cranial sutures
- Abnormality of the lymphatic system
- Alzheimer disease
- Atrioventricular canal defect
- Bilateral single transverse palmar creases
- Broad neck
- Clinodactyly of the 5th finger
- Decreased fertility
- Depressed nasal ridge
- Developmental regression
- Downturned corners of mouth
- Duodenal atresia
- Macroglossia
- Microdontia
- Narrow mouth
- Narrow palate
- Obesity
- Open mouth
- Polycythemia
- Prematurely aged appearance
- Protruding tongue
- Sandal gap
- Short nose
- Short stature
- Thick lower lip vermilion
- Thrombocytopenia
- Umbilical hernia
- Ventricular septal defect
Sometimes5–29%
25- Acute megakaryocytic leukemia
- Aganglionic megacolon
- Amblyopia
- Anal atresia
- Atlantoaxial dislocation
- Blepharitis
- Cataract
- Celiac disease
and 17 more in this range
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
ICD-10 codes
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Benefit programs to look at
Programs whose eligibility touches the same ICD-10 categories. Eligibility is decided by the administering agency, never by this page.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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