THE INFORMATION acquired during the past 25 years concerning that form of anemia which was described by Cooley and Lee in 19251 has led to a better understanding of the disorder. This type of anemia was separated from the heterogenous symptom complex known as von Jaksch's anemia, or infantile pseudoleukemia, and was recognized as a distinct disease entity. The early papers by Cooley2 described the condition as being characterized by a hypochromic microcytic anemia with many distorted erythrocytes which were usually resistant to hemolysis by hypotonic saline solution. Large numbers of nucleated erythrocytes in the normoblastic stage of development were encountered in the peripheral blood. Splenomegaly, episodes of jaundice and roentgenologic evidence of bone involvement were prominent features. The disease was usually seen in children of southern European parentage—Greek, Syrian or Italian peoples—though it has been reported from many other races over the world.3 The disease described