GSTM1 and anemia (phenotype): The low anaemia prevalence at 1–3 months is most likely attributable to the ‘physiologic anaemia’ period of infancy, in which an infant’s fetal Hb levels decrease in the 8–12 weeks after birth; this triggers erythropoiesis (production of new erythrocytes by the marrow) at around 3 months, allowing for a gradual recovery in Hb levels(30).