The patient’s eldest son (II-1) had subclinical hypothyroidism, and his thyroid function was as follows: TSH 4.97 mIU/L, fT4 1.41 ng/dL, T3 103.00 ng/dL, Tg antibody 16.3 IU/mL, TPO antibody 16.4 IU/mL, and TSH-receptor antibody 0.8 IU/L. Here, TPO is linked to thyroid gland disorder.