In particular, according to our recent retrospective pilot study, the addition of therapy with fluoxetine in patients with relapsing-remitting MS with a suboptimal response to the first-line DMT (IFN-β or glatiramer acetate) can reduce the disease activity, preventing the switching to the more aggressive second-line DMT (75). The gene discussed is IFNB1; the disease is relapsing-remitting multiple sclerosis.