GSTM1 and anemia (phenotype): For instance, in an otherwise thriving neonate with low hemoglobin, (1) both high Ret-Hb and reticulocyte counts may indicate sufficient capacity to correct anemia without further intervention; (2) low levels of reticulocyte but high levels of Ret-Hb may indicate there is enough iron but ineffective erythropoiesis; (3) low Ret-Hb and high reticulocyte counts may indicate effective erythropoiesis, but not enough iron available for normal hemoglobinization.