Finally, the WHO indicated that in people of African extraction, irrespective of age, the Hb anemia cutoff must be adjusted downwards by 1 g/dL [21], but in the study that was the basis for this correction (NHANES II), the difference found in African-American was 0.8 g/dL in children and 0.3 for adults [22]. Here, GSTM1 is linked to anemia (phenotype).