User:Mr. Ibrahem/Down syndrome
Medical condition / From Wikipedia, the free encyclopedia
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Down syndrome | |
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Other names | Down's syndrome, Down's, trisomy 21 |
Illustration of the facial features of Down syndrome | |
Specialty | Medical genetics, pediatrics |
Symptoms | Delayed physical growth, characteristic facial features, mild to moderate intellectual disability[1] |
Causes | Third copy of chromosome 21[2] |
Risk factors | Older age of mother, prior affected child[3][4] |
Diagnostic method | Prenatal screening, genetic testing[5] |
Treatment | Educational support, sheltered work environment[6][7] |
Prognosis | Life expectancy 50 to 60 years (developed world)[8][9][10] |
Frequency | 0.1% of newborns (5.4 million)[1][11] |
Deaths | 26,500 (2015)[12] |
Down 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.[2] It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features.[1] The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an 8- or 9-year-old child, but this can vary widely.[8]
The parents of the affected individual are usually genetically normal.[13] The probability increases from less than 0.1% in 20-year-old mothers to 3% in those of age 45.[3] The extra chromosome is believed to occur by chance, with no known behavioral activity or environmental factor that changes the probability.[14] Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing.[5] Since the introduction of screening, pregnancies with the diagnosis are often terminated.[15][16] Regular screening for health problems common in Down syndrome is recommended throughout the person's life.[8]
There is no cure for Down syndrome.[17] Education and proper care have been shown to improve quality of life.[6] Some children with Down syndrome are educated in typical school classes, while others require more specialized education.[7] Some individuals with Down syndrome graduate from high school, and a few attend post-secondary education.[18] In adulthood, about 20% in the United States do paid work in some capacity,[19] with many requiring a sheltered work environment.[7] Support in financial and legal matters is often needed.[9] Life expectancy is around 50 to 60 years in the developed world with proper health care.[8][9][10]
Down syndrome is one of the most common chromosome abnormalities in humans.[8] It occurs in about 1 in 1,000 babies born each year.[1] 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.[11][12][20] It is named after British doctor John Langdon Down, who fully described the syndrome in 1866.[21] Some aspects of the condition were described earlier by French psychiatrist Jean-Étienne Dominique Esquirol in 1838 and French physician Édouard Séguin in 1844.[22] The genetic cause of Down syndrome was discovered in 1959.[21]