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Genetic and Rare Diseases Information Center (GARD)

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Down syndrome


* Not a rare disease
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Other Names for this Disease

  • Down's syndrome
  • Trisomy 21
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.


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What are the signs and symptoms of Down syndrome?

People with Down syndrome may develop the following medical problems:[1] 

Children with Down syndrome are also more likely to develop chronic respiratory infections, middle ear infections, and recurrent tonsillitis. In addition, there is a higher incidence of pneumonia in children with Down syndrome than in the general population.[1]

Children with Down syndrome have developmental delay. They are often slow to turn over, sit, and stand. Developmental delay may be related to the child's weak muscle tone. Development of speech and language may also take longer than expected. Children with Down syndrome may take longer than other children to reach their developmental milestones, but many of these milestones will eventually be met.[1]

Adults with Down syndrome have an increased risk of developing Alzheimer disease, a brain disorder that results in a gradual loss of memory, judgment, and ability to function. Although Alzheimer disease is usually a disorder that occurs in older adults, about half of adults with Down syndrome develop this condition by age 50.[2]

Last updated: 6/8/2012

The Human Phenotype Ontology provides the following list of signs and symptoms for Down syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms.

Signs and Symptoms Approximate number of patients (when available)
Abnormality of calvarial morphology 90%
Abnormality of chromosome segregation 90%
Brachydactyly syndrome 90%
Cognitive impairment 90%
Depressed nasal bridge 90%
Epicanthus 90%
Joint hypermobility 90%
Malar flattening 90%
Muscular hypotonia 90%
Round ear 90%
Short neck 90%
Thickened nuchal skin fold 90%
Upslanted palpebral fissure 90%
Abnormality of immune system physiology 50%
Abnormality of the fontanelles and cranial sutures 50%
Abnormality of the lymphatic system 50%
Abnormality of the palate 50%
Clinodactyly of the 5th finger 50%
Decreased fertility 50%
Depressed nasal ridge 50%
Developmental regression 50%
Downturned corners of mouth 50%
Malformation of the heart and great vessels 50%
Microdontia 50%
Narrow mouth 50%
Obesity 50%
Open mouth 50%
Prematurely aged appearance 50%
Sandal gap 50%
Short nose 50%
Single transverse palmar crease 50%
Thick lower lip vermilion 50%
Umbilical hernia 50%
Abnormal hair quantity 7.5%
Abnormality of the intestine 7.5%
Acute leukemia 7.5%
Cataract 7.5%
Conductive hearing impairment 7.5%
Gait disturbance 7.5%
Hypothyroidism 7.5%
Impaired pain sensation 7.5%
Myopia 7.5%
Renal hypoplasia/aplasia 7.5%
Strabismus 7.5%
Type II diabetes mellitus 7.5%
Urogenital fistula 7.5%
Acute megakaryocytic leukemia -
Aganglionic megacolon -
Anal atresia -
Atlantoaxial instability -
Brachycephaly -
Broad palm -
Brushfield spots -
Complete atrioventricular canal defect -
Duodenal stenosis -
Hypoplastic iliac wings -
Intellectual disability -
Joint laxity -
Macroglossia -
Microtia -
Protruding tongue -
Shallow acetabular fossae -
Short middle phalanx of the 5th finger -
Short palm -
Short stature -
Sporadic -

Last updated: 9/2/2014

The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature.

The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined.

Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.

  1. Down syndrome. Genetics Home Reference Web site. 2005; . Accessed 10/9/2007.
  2. Down syndrome. Genetics Home Reference. June 2008; Accessed 6/1/2010.

Other Names for this Disease
  • Down's syndrome
  • Trisomy 21
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.