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Planning studies of etiology



Knowledge of the environmental and genetic etiologies of complex cognitive disorders can guide strategies for diagnosis, prevention, and therapy, but disentangling the various causes can be very challenging. Two basic approaches can be used in identifying genetic factors, a top-down approach, in which phenotypic descriptions are used to discover genes that influence those phenotypes, and a bottom-up approach, comparing the phenotypic effects of genes that are known to cause syndromes that include cognitive disabilities. Thorough characterization of phenotypes throughout development is critical to both of these methods. These strategies have been applied to the characterization of genetic etiologies for reading disability, language disorders, attention-deficit hyperactivity disorder, and autism.


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Shelley D. Smith, Munroe–Meyer Institute for Genetics and Rehabilitation, 985450 Nebraska Medical Center, Omaha, NE 68198-5450. E-mail:


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