TF and anemia (phenotype): There was a statistically significant unadjusted gene-by-gene interaction (βunadj = 0.37, p = 0.02) between the HFE and TF genotypes and, when adjusted for maternal blood lead level at delivery and child’s concurrent anemia status, this interaction term was marginally significant (βadj = 0.31, p = 0.06) (data not shown).