• mutants do not survive as newborns

• at E19.5, mutant fetuses are smaller than control fetuses

• at E17.5, mutant erythrocytees display notable anisocytosis, poikilocytosis, polychromasia, and targeting, characteristic of severe thalassemia

• virtually all mutant erythrocytes exhibit hemoglobin H inclusions

• at E17.5, hemoglobin H (beta4) is the major component constituting 55%-65% of total hemoglobin, as shown by isoelectric focusing electrophoresis

• at E17.5, mutant fetuses exhibit very high reticulocyte counts

• at E17.5, mutant fetuses display severe hemolytic anemia

• at E19.5, mutant fetuses are paler than control fetuses