GSTM1 and anemia (phenotype): According to the World Health Organization (WHO), the hemoglobin (Hb) limit for anemia is < 13 g/dL in men, <12 g/dL in women and < 11 g/dL in pregnant women.[3] The etiology of ID in developing countries is usually due to inadequate dietary Fe intake, malnutrition and chronic blood loss caused by intestinal parasites.[4] In developed countries, the best known causes are vegetarian diet, malabsorption and chronic blood loss due to heavy menstrual bleeding.