The current analysis showed that the content of two core-fucosylated IgG structures (F(6)A2G(4)2 and F(6)A2G(4)2S) was decreased in Hashimoto’s thyroiditis patients, while the level of F(6)A2 N-glycan assigned the most abundant UPLC peak was up-regulated in these patients (HT2) compared to the donors with the higher level of anti-Tg/anti-TPO (HT1) (Figure 3). The gene discussed is TPO; the disease is Hashimoto thyroiditis.