Nevertheless, this notion of a link between LBX1 function and hyperactivity as a hallmark of ADHD is further supported by the evidence that Lbx1 is required for specification of GABAergic neuron cell fate, which involves also the expression of peptide neuromodulators, such as neuropeptide y (NPY) [4]. This evidence concerns the gene LBX1 and attention deficit-hyperactivity disorder.