C57BL/6 (B6) mice and tyrosinase deficient B6 (B6.Tyr−/−) mice were infected with the lethal strain P. yoelii 17XL by injection of 104 infected red blood cells i.p. Mice were followed daily to evaluate parasitemia, body weight, temperature, clinical status, hemoglobin concentration and survival (Figure 1). The gene discussed is TYR; the disease is parasitic infectious disease.