This phenotype in the 5‐HTTOE mice connects with an emerging literature of an association between rare over‐expressing 5‐HTT gene variants and obsessive compulsive disorders as well as impulsive traits, which have long been linked to 5‐HT deficits (Hu et al., 2006; Wendland et al., 2008; Glenn, 2011; Voyiaziakis et al., 2011). Here, SLC6A4 is linked to obsessive-compulsive disorder.