One can quickly observe the presence of distinct themes in the hierarchical cloud generated by the query “Lep Bdnf Fto Lepr” (Lep, leptin; Bdnf, brain-derived neurotrophic factor; Fto, fat mass and obesity associated; Lepr, leptin receptor): obesity related words in the upper section, nervous system related words on the lower right, and, in the conjunction, depression related words on the lower left (Figure 3A). The gene discussed is BDNF; the disease is major depressive disorder.