GSTM1 and anemia (phenotype): The World Health Organization (WHO) defines childhood anemia as Hb concentration below 11 grams per deciliter in children between 6 and 59 months, below 11.5 grams per deciliter in children between 5 and 11 years, and below 12 grams per deciliter in children between 12 and 14 years of age (2).