Considering the range of other complexities across different populations, WHO has recently (2024) released an updated guideline [18] on Hb cutoffs to define anemia in individuals and populations to provide updated, locally adaptable, clear, evidence-informed normative statements on the use of Hb concentrations to assess anemia and on best approaches in its measurement in individuals and populations. This evidence concerns the gene GSTM1 and anemia (phenotype).