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Author's Response to Dr. Leo

Jonathan Leo raises issues with the adoption literature on schizophrenia [1]. These studies were intensively and independently scrutinized in the 1980s—see the series of papers by Kendler and Gruenberg (e.g., [2]). Most would agree that the number, size, and quality of adoption studies do not provide the highest-quality data (as discussed at more length elsewhere [3].

However, the salient point in my paper [4] was that this body of work (twin, adoption, and family studies) provides a consistent and solid rationale for the search for genes for schizophrenia.

Dr. Leo's comments about the treatment of schizophrenia are not within the scope of my paper.


  1. 1. Leo J (2006) Schizophrenia adoption studies. PLoS Med 3: e366. DOI:
  2. 2. Kendler KS, Gruenberg AM (1984) An independent analysis of the Danish Adoption Study of Schizophrenia. VI. The relationship between psychiatric disorders as defined by DSM-III in the relatives and adoptees. Arch Gen Psychiatry 41: 555–564.
  3. 3. Sullivan PF, Owen MJ, O'Donovan MC, Freedman RR (2005) Genetics. Washington (D. C.): American Psychiatric Publishing.
  4. 4. Sullivan PF (2005) The genetics of schizophrenia. PLoS Med 2: e212. DOI: