Down syndrome
Findings
No curated finding names Down syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Down syndrome is a chromosomal abnormality caused by the presence of a third (partial or total) copy of the chromosome 21 genetic material 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, or endocrine defects.
Definition from the Mondo Disease Ontology (MONDO:0008608), read 2026-09-29. CC BY 4.0.
- Onset and course
- Congenital onset
HPO, annotations 2026-09-02
Features
87 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Upslanted palpebral fissureHPOHP:0000582
- 440 of 524 reported patients
- Very frequent (80% to 99% of cases)
- BrachycephalyHPOHP:0000248
- Very frequent (80% to 99% of cases)
- BrachydactylyHPOHP:0001156
- 58 of 524 reported patients
- Very frequent (80% to 99% of cases)
- Depressed nasal bridgeHPOHP:0005280
- Very frequent (80% to 99% of cases)
- EpicanthusHPOHP:0000286
- Very frequent (80% to 99% of cases)
- Flat faceHPOHP:0012368
- Very frequent (80% to 99% of cases)
Show the remaining 75
- Specific learning disabilityHPOHP:0001328
- Very frequent (80% to 99% of cases)
- Thickened nuchal skin foldHPOHP:0000474
- Very frequent (80% to 99% of cases)
- Abnormal cardiovascular system morphologyHPOHP:0030680
- Frequent (30% to 79% of cases)
- Abnormal cranial suture/fontanelle morphologyHPOHP:0000235
- Frequent (30% to 79% of cases)
- Abnormality of blood and blood-forming tissuesHPOHP:0001871
- Frequent (30% to 79% of cases)
- Abnormality of immune system physiologyHPOHP:0010978
Where it sits
- A kind of
- Narrower terms (3)
Other names
4 names
Resolves to: Down syndrome
- Also called
- Down syndrome, Isolated casesDown's syndromeleukemia, megakaryoblastic, with or without Down syndrome, somatictrisomy 21 (Down syndrome)