Anemia, defined as the volume of packed red blood cells/hematocrit (Hct) or hemoglobin (Hb) concentration greater than two standard deviation (2SD) below mean for age, may be due to three general causes (i.e. blood loss, increased red blood cell (RBC) destruction or reduced RBC production) [1, 2]. The gene discussed is GSTM1; the disease is anemia (phenotype).