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Definition: Down's syndrome from Philip's Encyclopedia

Human condition caused by a chromosomal abnormality. It gives rise to varying degrees of mental retardation, decreased life expectancy, and perhaps physical problems, such as heart and respiratory disorders. The syndrome was first described by a British physician, J.L.H. Down. It is caused by the presence of an extra copy of chromosome 21, and detected by counting chromosomes in the cells of the fetus during pre-natal testing. There is evidence that the risk of having a Down's child increases with maternal age. Originally called 'Mongolism' by Down, this term is now obsolete.


Down Syndrome

From Encyclopedia of Global Health
Down syndrome, also called Down’s syndrome or trisomy 21, is a congenital disorder caused by the presence of all or part of an extra 21st chromosome. This gives people with Down syndrome 47 chromosomes, rather than 46. It acquired the name after the British doctor John Langdon Haydon Down (1828–1896) who first described it in 1866. The outward physical signs of the disorder, usually identified at birth, are a range of major and minor differences in body structure, including an impairment of cognitive ability and also physical growth. The incidence of Down syndrome is estimated at 1 for every 800 to 1,000 births, and it was first recognized by John L.H. Down as a different form of mental retardation in 1866, and four years later he published his report “Observations” on an Ethnic Classification of Idiots which was published in the Clinical Lecture Reports from London Hospital. Down, born in Torpoint, Cornwall, was from a well-connected family—his great-great grandfather on his father’s…
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Full text Article Down Syndrome

From Encyclopedia of Cognitive Science
Down syndrome is a chromosomal disorder characterized by specific dysmorphic features, organ malformations, and variable but often severe learning difficulties. Down syndrome (DS) is the most common known form of developmental disability. First described by Langdon Down in the London Hospital…
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Full text Article Down Syndrome

From Encyclopedia of Special Education: A Reference for the Education of Children, Adolescents, and Adults with Disabilities and Other Exceptional Individuals
Down syndrome, occurring in approximately 1 out of 800 to 1,000 live births ( National Dissemination Center for Children with Disabilities ,), is the most frequent genetic cause for Mild to Moderate Mental Retardation and associated medical problems ( National Institute of Child Health and Human…
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Full text Article Down Syndrome

From Gale Encyclopedia of Children's Health: Infancy Through Adolescence
(Lester V Bergman/Encyclopedia/Corbis)
Children...
Down syndrome is the most common chromosome disorder and genetic cause of intellectual disability. It occurs because of the presence of a third copy of chromosome 21. For this reason, it is also called trisomy 21. The Centers for Disease Control and Prevention (CDC) estimate that each year about…
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Full text Article Down Syndrome

From Gale Encyclopedia of Medicine
Down syndrome, or trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21 or by a portion of chromosome 21 translocated (attached) to another chromosome in one of the affected child's parents. It is not inherited in most cases but is caused by a random genetic…
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Full text Article Down Syndrome

From Gale Encyclopedia of Nursing and Allied Health
Down-syndrome karyotype, female. (Kateryna...
Down syndrome is the most common chromosome disorder and genetic cause of intellectual disability. It occurs because of the presence of an extra copy of chromosome 21. For this reason, it is also called trisomy 21. Chromosomes are the units of genetic information that exist within every cell of the…
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Full text Article Down Syndrome

From Gale Encyclopedia of Psychology
Color enhanced karyotype for a human female with...
Down syndrome is a broad-spectrum developmental disorder present at birth resulting from an abnormality in the number of inherited chromosomes. Down syndrome, also known trisomy 21, was named after John Langdon Haydon Down, who first described the condition in 1866. In 1959, the French pediatrician…
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Full text Article Down's Syndrome

From The Encyclopedia of Neuropsychological Disorders
Down's syndrome is a chromosomal disorder that may result from a number of cytogenic variants, resulting in the genetic mutation. Down's syndrome was first recognized as a formal set of physical characteristics in 1866 by Dr. John Langdon Down and later in 1959 was established to be the result of an…
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Full text Article Down Syndrome

From Human Diseases and Conditions
Alila Medical Media/Shutterstock.com. Chart...
Down syndrome is a genetic 990 condition that occurs when a person has three copies of chromosome 21, rather than the usual two. People with Down syndrome usually have a characteristic physical appearance, significantly lowered intellectual abilities, and sometimes a number of physical problems, …
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Full text Article Down Syndrome

From Brenner's Encyclopedia of Genetics
Boy with trisomy 21.
Abstract Trisomy 21 is the commonest autosomal trisomy in humans. The extra chromosome 21 may cause a variety of congenital malformations and medical problems, especially affecting the heart, growth, and learning. In most but not all cases, the extra chromosome 21 is derived from the egg and it…
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Full text Article Down Syndrome

From Encyclopedia of Autism Spectrum Disorders
Down’s syndrome ; Trisomy 21 This condition, first described by Langdon Down in the 1860s, is caused by the presence of three copies of chromosome 21 (trisomy 21). The tri-somy can reflect an entire extra copy of chromosome 21 or a partial one (the latter due to translocation). At one time, a very…
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