Sickle cell anemia (SCA) is the most common hereditary disorder of hemoglobin synthesis characterized by a mutation in the β globin gene, which leads to the replacement of glutamic acid with valine at the sixth codon and synthesis of Hb S a hemoglobin which, under hypoxic conditions, gels leading to the sickening of the red blood cells (RBC). The gene discussed is GSTM1; the disease is sickle cell disease.