Nosology and epidemiology in autism: Classification counts


  • Gene S. Fisch

    Corresponding author
    • Department of Epidemiology and Health Promotion, NYU Colleges of Dentistry and Nursing, 250 Park Ave. S., 6th fl., New York, NY 10003.
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    • Dr. Gene S. Fisch is a Senior Biostatistician and Research Professor at the NYU Colleges of Dentistry and Nursing in New York City and Adjunct Professor of Statistics at Yeshiva University in New York. He has been a biostatistician and research scientist for 25 years at various institutions. His research interests include: cognitive-behavorial features and development in children with the fragile X mutation, Williams-Beuren syndrome, Neurofibromatosis type 1, and the genetics of autism.


This article is corrected by:

  1. Errata: Erratum: In the article by Gene S. Fisch, entitled “Nosology and Epidemiology in Autism: Classification Counts,” in. American Journal of Medical Genetics Part C (Seminars in Medical Genetics) 160C:91–103 10.1002/ajmg.c.31325 (2012) Volume 161, Issue 9, 2399, Article first published online: 14 August 2013

  • How to cite this article: Fisch GS. 2012. Nosology and epidemiology in autism: Classification counts. Am J Med Genet Part C Semin Med Genet 160C:91–103.


Since its initial description by Kanner in 1943, the criteria by which a diagnosis of autism or autism-like disorders was made—and their alleged etiologies portrayed—have undergone manifold changes, from a psychiatric disorder engendered by “refridgerator” parents to a neurodevelopmental disability produced in the main by genetic abnormalities. In addition, the behavioral characterization of autism has also entered the public consciousness and professional domains increasingly in the past 30 years, the effects of which we are continually coming to terms. A diagnosis of autism that once seemed quite unusual is now considered almost epidemic. Increasing numbers of individuals diagnosed with autism and related pervasive developmental disabilities will, in turn, affect the calculated prevalence of the disorder. In this essay, I attempt to account for the increasing prevalence of autism and autism-related disorders by examining its changing criteria, the individuals and instruments used to make the diagnosis, the reliability and validity of same, and the sample sizes and other aspects of the methodology needed to make an accurate estimate of its prevalence. © 2012 Wiley Periodicals, Inc.