448GLUTATHIONE S-TRANSFERASE M1NULL GENE POLYMORPHISM AND RISK OF CMLA hematological malignancy marked by a sustained increase in the number of granulocytes, splenic enlargement and a specific cytogenetic anomaly (the ―Philadelphia chromosome‖) in the bone marrow of morethan90% of patients. Glutathione sulfur tranferase (GSTs) is a group of enzymes involved in the detoxification process of carcinogens and other substances. The genes encoding is enzymes M1 and T1 are polymorphic in humans and the phenotypic absence of enzyme activity (null genotype) may have an effect on the risk of chronic myeloid leukemia (CML). Objective to study the association between Glutathione S-transferes gene polymorphism (M1null) and CML. Patients and Samples. A total of 50 Sudanese patients with chronic myeloid leukemia attended to radiation and isotopes center of Khartoum (RICK) Sudan, during the period from May to September 2014 were enrolled in this study, their age ranged between 40-78 years also 50 individual were enrolled as control group in this study their age ranged between 42-75. 2.5 ml of venous blood was collected from each subject in (E.D.T.A) container for molecular analysis, and informed consent was taken from each participant. DNA was extracted from (E.D.T.A) anticoagulated blood sample using kit method. A total of 50 patients diagnosed with CML attending to the radiation and isotope center of Khartoum (RICK) Sudan, and 50 healthy volunteer as control group were enrolled in this study .For molecular analysis genomic DNA was extracted from participant`s EDTA anticoagulated blood samples by kit method and analyzed by allele specific PCR for determination of GST M1null. A total of 50 patients diagnosed with CML attending to the RICK, their ages ranged between11-75 years 28(56%) of them are male and 22(44%) of them are female, they were correlate with 50 healthy volunteers as control group their ages ranged between 42-75 years, there was 7(14%) of patients were suffering from hepatomegaly , 29 (58%) of patients were suffering from splenomegaly and 14 (28%)of patients were suffering from splenohepatomegaly. The frequency of GSTM1 null is about 54% (27 patient) among CML patient and m1null is about 46% (23 patient) among CML patient. Our results demonstrate that GSTM1 polymorphism is not associated with CML in Sudanese population.ibrahimkh82@gmail.comResearch612016Hematological malignancy,DNA ExtractionHaythem salah zaki, Ibrahim Khider IbrahimDepartment of Haematology, Faculty of Medical Laboratory Sciences, Al Neelain University, Sudan.,Department of Haematology, Faculty of Medical Laboratory Sciences, Al Neelain University, Sudan.