

People with Down syndrome may have some or all of these physical characteristics: a small chin, slanted eyes, poor muscle tone, a flat nasal bridge, a single crease of the palm, and a protruding tongue due to a small mouth and relatively large tongue. Characteristicsįeet of a boy with Down syndrome, showing the deviated first toes

They have an increased risk of a number of other health problems, including congenital heart defect, epilepsy, leukemia, thyroid diseases, and mental disorders. They also typically have poor immune function and generally reach developmental milestones at a later age. As adults, their mental abilities are typically similar to those of an 8- or 9-year-old. Those with Down syndrome nearly always have physical and intellectual disabilities. The genetic cause of Down syndrome was discovered in 1959. Some aspects of the condition were described earlier by French psychiatrist Jean-Étienne Dominique Esquirol in 1838 and French physician Édouard Séguin in 1844. It is named after British doctor John Langdon Down, who fully described the syndrome in 1866. In 2015, Down syndrome was present in 5.4 million individuals globally and resulted in 27,000 deaths, down from 43,000 deaths in 1990. It occurs in about 1 in 1,000 babies born each year.

ĭown syndrome is one of the most common chromosome abnormalities in humans. Regular screening for health problems common in Down syndrome is recommended throughout the person's life. Life expectancy is around 50 to 60 years in the developed world with proper health care. Support in financial and legal matters is often needed. In adulthood, about 20% in the United States do paid work in some capacity, with many requiring a sheltered work environment. Some individuals with Down syndrome graduate from high school, and a few attend post-secondary education. Some children with Down syndrome are educated in typical school classes, while others require more specialized education. Education and proper care have been shown to improve quality of life. Since the introduction of screening, Down syndrome pregnancies are often aborted. Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing. The extra chromosome is believed to occur by chance, with no known behavioral activity or environmental factor that changes the probability. The probability increases from less than 0.1% in 20-year-old mothers to 3% in those of age 45. The parents of the affected individual are usually genetically normal. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. Life expectancy 50 to 60 years (developed world) ĭown syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. Older age of mother, prior affected child Įducational support, sheltered work environment

Illustration of the facial features of Down syndromeĭelayed physical growth, characteristic facial features, mild to moderate intellectual disability
