CAT and thalassemia: Thalassemia is the hemolytic disorder with phenotypicheterogeneity and causes a wide range of symptoms [1].Moreover, the understanding of the phenotype-genotypecorrelation is difficult due to modifying factors in thalassemia [2].Several studies have been demonstrated that the occurringvariation in some genes, such as HBA1, HBA2, HBB, HBG1,HBG2, BCL11A, COL1A1, CAT and GST genes can moderate theseverity of thalassemia [16,17, 18,19, 20].