Specifically, X-monosomic mice (which exhibit neither short stature nor gross hormonal abnormalities) exhibit attentional deficits that can be rescued by the presence of a small chromosome housing Sts [58]; moreover, mice lacking the Sts gene, or mice in which the associated steroid sulfatase enzyme is inhibited, show attentional deficits and other phenotypes of relevance to ADHD [42, 47, 59, 60]. This evidence concerns the gene STS and attention deficit-hyperactivity disorder.