Indeed, if one or more psychiatric disorders eventually prove to be pathway diseases, there could be clinical benefit. We conjecture that it might be considerably easier to coax an existing but dysfunctional biological pathway into the normal range than to replace components broken by Mendelian mutations. Moreover, in an era where many drug companies have moved away from drug development for psychiatric disorders, 139 the ability to measure such a hypothetical pathway in an appropriate cellular system could enable chemical biology screens of existing and novel compounds as well as the evaluation of the rational use of multiple compounds simultaneously.
