A chromosomal dysgenesis syndrome resulting from a triplication or translocation of chromosome 21. Down syndrome occurs in approximately 1:700 live births. Abnormalities are variable from individual to individual and may include mental retardation, retarded growth, flat hypoplastic face with short nose, prominent epicanthic skin folds, small low-set ears with prominent antihelix, fissured and thickened tongue, laxness of joint ligaments, pelvic dysplasia, broad hands and feet, stubby fingers, transverse palmar crease, lenticular opacities and heart disease. Patients with Down syndrome have an estimated 10 to 30-fold increased risk for leukemia; most have symptoms of Alzheimer's disease by age 40. Also known as trisomy 21 syndrome.

A chromosome disorder associated either with an extra CHROMOSOME 21 or an effective TRISOMY for chromosome 21. Clinical manifestations include HYPOTONIA, short stature, BRACHYCEPHALY, upslanting palpebral fissures, epicanthus, Brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, single transverse palmar crease, and moderate to severe INTELLECTUAL DISABILITY. Cardiac and gastrointestinal malformations, a marked increase in the incidence of LEUKEMIA, and the early onset of ALZHEIMER DISEASE are also associated with this condition. Pathologic features include the development of NEUROFIBRILLARY TANGLES in neurons and the deposition of AMYLOID BETA-PROTEIN, similar to the pathology of ALZHEIMER DISEASE. (Menkes, Textbook of Child Neurology, 5th ed, p213)

A disorder caused by the presence of an extra chromosome 21 and characterized by mental retardation and distinguishing physical features.

Down syndrome is a condition in which a person has an extra chromosome or an extra piece of a chromosome. This extra copy changes how a baby's body and brain develop. It can cause both mental and physical challenges during their lifetime. Even though people with Down syndrome might act and look similar, each person has different abilities. Chromosomes are tiny "packages" in your cells that contain your genes. Genes carry information, called DNA, that controls what you look like and how your body works. People with Down syndrome have an extra copy of chromosome 21. In some cases, they may have an extra copy of part of the chromosome. Having an extra copy of a chromosome is called trisomy. So sometimes Down syndrome is also called trisomy 21. Down syndrome is usually not inherited. It happens by chance, as an error when cells are dividing during early development of the fetus. It is not known for sure why Down syndrome occurs or how many different factors play a role. One factor that increases the risk of having a baby with Down syndrome is the age of the mother. Women ages 35 and older are more likely to have a baby with Down syndrome. The symptoms of Down syndrome are different in each person. And people with Down syndrome may have different problems at different times of their lives. They usually have mild to moderate intellectual disabilities. Their development is often delayed. For example, they may start talking later than other children. Some of the common physical signs of Down syndrome include: A flat face; Eyes that slant up; A short neck; Small hands and feet; Poor muscle tone; Loose joints. Many people with Down syndrome have the common physical signs and have healthy lives. But some people with Down syndrome might have one or more birth defects or other health problems. Some of the more common ones include: Hearing loss; Sleep apnea (a disorder that causes you to repeatedly stop breathing during sleep); Ear infections; Eye diseases; Congenital heart defects (heart defects that are present at birth); Digestive problems; Problems with the upper part of the spine; Obesity. Health care providers can check for Down syndrome during pregnancy or after a child is born. There are two basic types of tests that help find Down syndrome during pregnancy: Prenatal screening tests can show whether your unborn baby has a higher or lower chance of having Down syndrome. If a screening test shows that your baby could have Down syndrome, you'll need another test to find out for sure.; Prenatal diagnostic tests can diagnose or rule out Down syndrome by checking the chromosomes in a sample of cells. These tests have a small risk of causing a miscarriage, so they're often done after a screening test shows that an unborn baby could have Down syndrome. After a baby is born, the provider may make an initial diagnosis of Down syndrome based on the physical signs of the syndrome. The provider can use a karyotype genetic test to confirm the diagnosis. The test can check for extra chromosomes in a sample of the baby's blood. There is no single, standard treatment for Down syndrome. Treatments are based on each person's physical and intellectual needs, strengths, and limitations. Services early in life focus on helping children with Down syndrome develop to their full potential. These services include speech, occupational, and physical therapies. They are typically offered through early intervention programs in each state. Children with Down syndrome may also need extra...

Chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21; clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, simian crease, and moderate to severe mental retardation.

Down syndrome is an anomaly of chromosome 21 that can cause intellectual disability, microcephaly, short stature, and characteristic facies. Diagnosis is suggested by physical anomalies and abnormal development and confirmed by cytogenetic analysis. Management depends on specific manifestations and anomalies.

Down syndrome is by far the most common and best known chromosomal disorder in humans and the most common cause of intellectual disability. It is characterized by intellectual disability , dysmorphic facial features, and other distinctive phenotypic traits.

Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical features of Down syndrome.

Down syndrome is a chromosome disorder associated with intellectual disability, a characteristic facial appearance, with small nose and an upward slant to the eyes, and low muscle tone in infancy. The degree of intellectual disability varies from mild to moderate. People with Down syndrome may also be born with various health concerns...

Down syndrome (DS), or trisomy 21, is the most common genetic form of intellectual disability, occurring in 1 in 691 births. In addition to having characteristic physical features, short stature, and hypotonia, individuals with DS have a distinctive cognitive and behavioral profile. They also have a higher frequency of associated medical...

Down syndrome, congenital disorder caused by the presence in the human genome of extra genetic material from chromosome 21. The affected individual may inherit an extra part of chromosome 21 or an entire extra copy of chromosome 21, a condition known as trisomy 21. British physician John Langdon...