The critical effect of Pb in the human body is mainly attributed to cellular enzymatic disruption of δ-aminolevulinic acid dehydratase (ALAD) that is essential in heme biosynthesis with a consequent decrease in various red blood cell hematological parameters (RDW-CV, MCV, MCH, and hematocrit) and potential risk of anemia [9, 44, 45]. The gene discussed is ALAD; the disease is anemia (phenotype).