RT Journal A1 DeLisi LE T1 NEuroleptic responsiveness in siblings concordant for schizophrenia JF Archives of General Psychiatry JO Archives of General Psychiatry YR 1989 FD May 1 VO 46 IS 5 SP 477 OP 477 DO 10.1001/archpsyc.1989.01810050091014 UL http://dx.doi.org/10.1001/archpsyc.1989.01810050091014 AB To the Editor.—  Recently we reported the results of a clinical examination of siblings who were concordant for schizophrenia.1 We have received queries from several interested colleagues as to whether, in addition to the clinical characteristics we noted, we also were able to detect whether pharmacologic response to antipsychotic medication was similar within families. The interest in this issue is twofold: (1) response to neuroleptics is known to have a strong genetic basis, and thus could be hypothesized to be related to the genetics of schizophrenia; and (2) faced with the potential heterogeneity of the cause of schizophrenia, division of subjects by pharmacologic responsiveness to define specific biologic entities could be a valid method of classification. Siblings concordant for schizophrenia could be examined to test these hypotheses based on the assumption that within each family schizophrenic illness will have the same cause, genetic vulnerability, and pathogenesis. Treatment response, however,