Castellan-Baldan et al. (2014) reported that histamine infusion into the brain reduced behavioral abnormalities, dopamine levels and D2/D3 dopamine receptor binding in the striata of histidine decarboxylase-knockout mice, suggesting that histidine decarboxylase deficiency in the basal ganglia alters histaminergic and dopaminergic neurotransmission, which may be an important pathological feature of Tourette Syndrome [26]. The gene discussed is HDC; the disease is Tourette syndrome.