Hall Hall KT KT Lembo Lembo AJ AJ Kirsch Kirsch I I Ziogas Ziogas DC DC Douaiher Douaiher J J Jensen Jensen KB KB Catechol-O-methyltransferase val158met polymorphism predicts placebo effect in irritable bowel syndrome Catechol-O-methyltransferase val158met polymorphism predicts placebo effect in irritable bowel syndrome 2012 2012. Here, COMT is linked to irritable bowel syndrome.