Down Syndrome

Down syndrome, congenital disorder characterized by mild to severe mental retardation, slow physical development, and characteristic physical features. Down syndrome affects about 1 in every 730 live births and occurs in all populations equally. It was first described in 1866 by an English physician, J. Langdon Down. In 1959 a French physician, Jerome Lejeune, discovered that the syndrome was caused by an extra chromosome. It was later discovered that this extra chromosome appears as a third chromosome attached to the 21st of the 23 pairs of chromosomes normally present in the human genome. This third chromosome gives rise to the alternate name trisomy 21.

The extra genetic material is responsible for the physical characteristics of the syndrome: low muscle tone, flattish facial features, an upward slant to the eyes and epicanthal folds (which were the basis for the former name, mongolism), a single crease across the palm, hyperflexibility of the joints, and a displastic middle phalanx on the fifth finger. People with Down syndrome have an increased incidence of infection, childhood leukemia, congenital heart defects, and respiratory problems, but modern medical treatment has improved the life expectancy from 9 (in 1910) to 55 (in 1995).

Mental retardation varies widely, from minimal to severe. The great majority of those who have the disorder attend public schools and as adults can live independently or in group homes. After age 35 individuals with the syndrome develop the neurological changes of Alzheimer's disease, and many develop the dementia that accompanies them.

Eighty percent of children with Down syndrome are born to women under 35 years of age, but the incidence of Down syndrome births does increase with age. Approximately 5% of cases are transmitted by the sperm. Amniocentesis or chorionic villus sampling can be used to detect the disorder in the fetus. Children born to women with Down syndrome have a 50% chance of having the disorder.

The Columbia Encyclopedia, 6th ed. Copyright© 2013, The Columbia University Press.

Selected full-text books and articles on this topic

Families and Their Children with Down's Syndrome: One Feature in Common
Elizabeth A. Byrne; Cliff C. Cunningham; Patricia Sloper.
Routledge, 1988
Early Intervention in Transition: Current Perspectives on Programs for Handicapped Children
Kofi Marfo.
Praeger Publishers, 1991
Librarian’s tip: Chap. 3 "Down Syndrome and Cognitive Enhancement: Not like the Others"
Emotional Development in Atypical Children
Michael Lewis; Margaret Wolan Sullivan.
Lawrence Erlbaum Associates, 1996
Librarian’s tip: Chap. 6 "Expression and Understanding of Emotion in Atypical Development: Autism and Down Syndrome"
Developmental Language Disorders: From Phenotypes to Etiologies
Mabel L. Rice; Steven F. Warren.
Lawrence Erlbaum Associates, 2004
Librarian’s tip: Chap. 5 "Language, Social Cognition, Maladaptive Behavior, and Communication in Down Syndrome and Fragile X Syndrome"
Intervention to Improve Expressive Grammar for Adults with Down Syndrome
Hewitt, Lynne E.; Hinkle, Angela S.; Miccio, Adele W.
Communication Disorders Quarterly, Vol. 26, No. 3, Spring 2005
Beyond Names for Things: Young Children's Acquisition of Verbs
Michael Tomasello; William E. Merriman.
Lawrence Erlbaum Associates, 1995
Librarian’s tip: Chap. Eleven "Syntactic Bootstrapping from Start to Finish with Special Reference to Down Syndrome"
What General Educators Have to Say about Successfully Including Students with Down Syndrome in Their Classes
Wolpert, Gloria.
Journal of Research in Childhood Education, Vol. 16, No. 1, Fall-Winter 2001
Testing Women, Testing the Fetus: The Social Impact of Amniocentesis in America
Rayna Rapp.
Routledge, 1999
Librarian’s tip: Chap. 10 "The Unexpected Baby"
Personality and Motivational Differences in Persons with Mental Retardation
Harvey N. Switzky.
Lawrence Erlbaum Associates, 2001
Librarian’s tip: "Direct Effects on Personality-Motivational Functioning: The Example of Down Syndrome" begins on p. 263
Progress in Infancy Research
Carolyn Rovee-Collier; Lewis P. Lipsitt; Harlene Hayne.
Lawrence Erlbaum Associates, vol.1, 2000
Librarian’s tip: Chap. 3 "Down Syndrome: Neuropsychology and Animal Models"
Children with Down Syndrome: Discovering the Joy of Movement
Jobling, Anne; Virji-Babul, Naznin; Nichols, Doug.
JOPERD--The Journal of Physical Education, Recreation & Dance, Vol. 77, No. 6, August 2006
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