Sir.—I do not believe that the findings we presented are in conflict with the references cited by Dr. Koenig.
Microcythemia is not found in all subjects with the α thalassemia trait of black Americans. Among the subjects with this condition studied by Schwartz and Atwater, only seven of 14 had an MCV less than 77 cu μ.1 Nor are red blood cell (RBC) indexes in β thalassemia trait consistent; an equation using RBC indexes to distinguish iron deficiency from β thalassemia trait in a black population has not been described. In our study, a quantitative A2 determination was performed on blood samples taken from those children with microcythemia, not on the originally screened population of 1,210 school children.
The finding of microcythemia in a school child living in the social conditions we have described suggests suboptimal iron nutrition and warrants an examination of the child and his