Clinical components of MAS include prolonged fever, lymphadenomegaly, splenomegaly, hemorrhage, cytopenias that affect at least two leukocyte lineages, thrombocytopenia, hypoproteinemia, elevated liver enzymes, hemophagocytosis, tissue infiltration by activated macrophages, hyperferritinemia, and elevated soluble CD163 (sCD163) [51]. The gene discussed is CD163; the disease is macrophage activation syndrome.