In HT patients, Th1 cells are the dominant infiltrating lymphocytes, which release cytokines (IFN-γ, IL-2, and TNF-α) under the stimulation of thyroid autoantigen, and the latter stimulates the expression of Fas on the surface of the thyroid cells, thereby accelerating the apoptosis of the thyroid cells (75). The gene discussed is IFNG; the disease is hematocrit.