Placebo

Placebo is a simulated or otherwise medically ineffectual treatment intended to deceive the recipient. Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect.

rs4680 influences the effectiveness of placebo.

rs4570625(G;G) homozygosity was a significant predictor of clinical placebo response, being associated with greater improvement in anxiety symptoms.

rs4570625, also known as G-703T, is a SNP in the tryptophan hydroxylase 2 TPH2 gene. This SNP has been linked to several psychiatric and/or behavioural phenomena, including:

rs4570625 and rs4565946 linked to the pathogenesis of early-onset obsessive compulsive disorder

rs4570625 and rs11178997 in TPH2's regulatory region display preferential transmission

https://www.nytimes.com/2018/11/07/magazine/placebo-effect-medicine.html