TACR1 and attention deficit-hyperactivity disorder: We have suggested that the abnormal behavioural profile of mice with functional ablation of the neurokinin-1 receptor (Nk1r) gene (NK1R-/-) is analogous to that of a subgroup of attention deficit hyperactivity disorder (ADHD) patients with polymorphism(s) of the TACR1 gene (the human equivalent of Nk1r; Sharp et al., 2014; Yan et al., 2010).