HT is an autoimmune disease in which Treg cells play a crucial role in preventing the onset and progression by suppressing the production of harmful autoantibodies targeting thyroglobulin (TG) and thyroid peroxidase (TPO) (35) by autoreactive B cells, thus preventing the destruction caused by these autoreactive B cells (36, 37). The gene discussed is TPO; the disease is hematocrit.