In contrast, in a Brazilian study assessing vitamin D status in relation to cytokines produced by Th1 (IL-2, IFN-γ, TNF-α), Th2 (IL-4, IL-5), and Th17 (IL-17) cells in 88 patients with HT and 71 euthyroid healthy subjects, the authors observed a positive correlation between vitamin D and IL-17, TNF-α, and IL-5 in HT patients only, which might be explained by the control of cytotoxicity resulting from long-time treatment of HT based on levothyroxine replacement therapy [195]. The gene discussed is TNF; the disease is hematocrit.