More recently, when plasma levels of IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ were determined during the follow-up of anti-TB chemotherapy, slow responders showed significantly higher IL-2 and IL-4 levels at baseline than did fast responders, effectively differentiating the two responder types (Iqbal et al., 2016). The gene discussed is IL2; the disease is tuberculosis.