Glutathione S-transferases (GSTs) are a supergene family of detoxifying enzymes which are found in virtually all life forms [1]. GSTs are phase II detoxifying enzymes that catalyze the conjugation of reduced glutathione with a wide variety of electrophilic substrates [2]. In addition to their function in xenobiotic detoxification, GSTs have peroxidase and isomerase activities that can inhibit the c-Jun N-terminal kinase (JNK) [3]. GSTs can also bind non-catalytically with a wide range of endogenous and exogenous ligands [3].

In humans, GST enzymes consist of many cytosolic, mitochondrial, and microsomal proteins, and the cytosolic family has eight distinct classes: alpha (A), kappa (K), mu (M), omega (O), pi (P), sigma (S), theta (T), and zeta (Z)[1][4].

Polymorphisms within genes that encode GSTs have been associated with susceptibility to nonmalignant[5]and malignant human diseases, [6] including acute myeloid leukemia (AML). [7]. Presumably, altered cancer risk because of polymorphic variation is mediated by differential ability to conjugate and detoxify both endogenously formed and exogenously derived electrophiles and their metabolites. Due to their multiple functions, polymorphic variants of GST enzymes may account for interindividual differences in outcome of chemotherapy. There are several reports on the role of GSTM1 and/or GSTT1 deletions as prognosticators in acute leukemia. [8][9].

To our best of knowledge this is the first study conducted in to determine the frequency of GSTM1 and GSTT1 polymorphisms in AML patients and their possible association with AML in a Sudanese population.

This is a descriptive case control study conducted in Khartoum state during the period from October 2014 to March 2015. Patients group was obtained at Flow Cytometry Laboratory Center at Khartoum, Sudan, where the patients were referred for immunophenotypic diagnosis.

Blood samples (3ml) were collected from 40 patients and 40 controls in ethylene diamine tetra acetic acid (EDTA) containers and genomic DNA was extracted by salting out method [10]. All patients and controls sampled in the study were consented verbally and the study was approved by the Human Ethics Committee of Al Neelan University.

Genotyping for detection of GSTM1, and GSTT1 polymorphisms was performed for both patients and controls using a multiplex PCR modified from Abdel-Rahman[11].

PCR amplification was carried out in 25 μl reactions containing three microliter (μl) of DNA , 1μl of each primer (Table 1), 4μl Matser mix (GoTaq® Green Master Mix, Promega, USA) and 12 μl of nuclease free water.

Thermal cycling conditions were as follows: an initial denaturation step at 95̊ C for 5 min, 35 cycles at 94̊ C for 1 min, 60̊ C for 1 min and 72̊ C for 1 min, and a final extension step at 72̊ C for 5 min (Table 1).

For analysis, 5 μl of each PCR product was fractionated on a 2% agarose gel with 0.05 μg/ml ethidium bromide. PCR products were directly visualized using UV fluorescence. GSTM1 & GSTT1 genotypes were determined by the presence and absence (null) of bands of 230 bp and 480 bp, respectively, with an internal control of 500 bp ( Figure 1) .

The frequency of subjects carrying the GSTM1 null polymorphism was significantly higher in AML patients (60.7%) compared to controls (36 %) (OR= 2.7, 95% CI= 1.2-6.04, p.value= 0.012). For the GSTM1 normal genotype frequencies were 39.3 % in patients’ group and 64 % in controls’ group. (Table 2).

The frequencies of GSTT1 null genotype were higher in AML patients (60 %) than in control`s group (23.4%). However, for the GSTT1 normal genotype frequencies were 40 % in patients’ group and 76.7% in controls’ group. Statistically, significant difference was observed (OR= 4.93, 95% CI= 1.6-15.07; p.value= 0.005) (Table 2).

We are indebted to all the patients who participated in the study. We would also like to thank our technical colleagues (Molecular Biology Laboratory, Faculty of Medical Laboratory Sciences, Al Neelan University).

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