The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

mental retardation

A mental disorder characterized by significantly subaverage general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period; classified as...

mild (IQ 50-70) - can develop social and communication skills during the preschool period, have minimal sensorimotor impairment, can by their late teens learn academic skills up to the sixth grade level, and usually achieve social and vocational skills adequate for minimal self-support;

moderate (IQ 35-50) - can talk or learn to communicate but have poor social awareness and only fair motor development, are unlikely to progress to the second grade level in academic skills but can profit from vocational training, and can take care of themselves under supervision;

severe (IQ 20-35) - have poor motor development and minimal speech in the preschool period, may learn to talk by their late teens and can be trained in elementary hygiene skills, and as adults may learn to perform simple work under close supervision;

profound (IQ below 20) - have limited sensorimotor development, may achieve very limited self-care, and require a highly structured environment and constant supervision.

Borderline mental retardation (IQ 70-85), now called borderline intellectual functioning, is used to refer to very mild forms with only slight impairments in adaptive behavior.

Called also mental deficiency or subnormality.