Two children with thalassemia identified during screening for anemia in junior high school.

We present two Japanese students with thalassemia identified during screening for anemia in their junior high school. Blood test results revealed marked hypochromic and microcytic erythrocytosis in one patient and microcytic anemia in the other. Both cases showed a mean corpuscular volume/red blood cell (MCV/RBC) ratio less than 13. Their beta/alpha synthesis ratio was elevated. Deletion of psialpha2, psialpha1, alpha2, alpha1 and theta1 genes in the alpha-globin gene clusters were noted in the first case. This pattern of gene deletion was consistent with heterozygous alpha-thalassemia 1 of the Southeast Asian type. On the other hand, an increased hemoglobin A2 level and reduced beta/alpha synthesis ratio were found in the second case. Direct cloning and DNA sequencing identified a point mutation (guanine to adenine) at position 1 of intervening sequence II in the beta-globin gene (IVS II-1 G-->A). These results suggest that this patient had heterozygous beta0-thalassemia. Diagnosis of thalassemia should be confirmed by molecular analysis in cases with microcytic anemia or hypochromic microcytosis with a MCV/RBC ratio of 13 or less.