Interestingly, a similar phenomenon was also found in our present study, and the following findings can indicate KD tends to develop MAS: (1) splenomegaly, decreased PLT count, hypoproteinemia, hypofibrinogenemia, hyperlipidemia, hyperferritinemia, and elevation of transaminases and LDH levels on admission; (2) a significant increase in serum ferritin and TG levels, and a significant decrease in Hb level before and 36–72 h after the first dose of IVIG treatment (3); IVIG-resistance KD. The gene discussed is GSTM1; the disease is macrophage activation syndrome.