Ethics of predictive testing for Huntington's chorea: the need for more information.

The finding of a genetically linked polymorphic DNA marker has made possible a predictive test for Huntington's chorea. This DNA probe has so far been used only for research and has technical limitations, but some workers now wish to apply it to clinical predictions. Those identified by the probe as being probable carriers of the Huntington's chorea gene would be exposed to uncertain psychological risks and social pressures. Ethical guidelines should be established, but these require greater knowledge of the potential benefits and hazards of this powerful new procedure. Controlled clinical trials are urgently needed.