Role of glutathione S-transferase M1, T1 and P1 gene polymorphisms in childhood acute lymphoblastic leukemia susceptibility in a Turkish population

Association Between the Individual and Combined Effects of the GSTM1 and GSTT1 Polymorphisms and Risk of Leukemia: A Meta-Analysis

Background: Fourteen meta-analyses reported the individual effects of the GSTM1 and GSTT1 polymorphisms on leukemia risk. However, over 40 studies were not included in previously published meta-analyses. Moreover, one key aspect was that previous meta-analyses did not conduct the false-positive test on the aforementioned issues. Furthermore, previous meta-analyses did not observe the combined effects of GSTM1 present/null and GSTT1 present/null polymorphism with leukemia risk. Therefore, we conducted the current study to further analyze these associations. Objectives: This study aimed to investigate the association between the individual and combined effects of the GSTM1 present/null and GSTT1 present/null polymorphisms and the risk of leukemia. Methods: A meta-analysis was performed applying Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines. Moreover, false-positive report probability (FPRP) and Bayesian false discovery probability (BFDP) were applied to investigate the false-positive results. Results: The individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes were associated with a significantly increased leukemia risk in overall and several subgroup analyses, such as Asians, Caucasians, and so on. Then, further analysis was conducted using FPRP and BFDP. Significant associations were considered as "positive" results on the GSTM1 null genotype with leukemia risk in overall populations (FPRP < 0.001 and BFDP = 0.006), Asians (FPRP < 0.001 and BFDP < 0.001), and East Asian population (FPRP < 0.001 and BFDP = 0.002). For the GSTT1 null genotype, significant associations were regarded "positive" results in overall populations, acute myeloid leukemia (AML), Asians, and East Asian population. For the combined effects of the GSTM1 and GSTT1 polymorphisms, significant associations were also considered "positive" results in the overall analysis of Asians, Indians, and East Asian population. Conclusion: This study strongly indicates that the individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes are associated with increased leukemia risk in Asians, especially in the East Asian population; the GSTT1 null genotype is associated with increased AML risk; the combined effects of the two genes are associated with increased leukemia risk in Indians.

Genetic variants of glutathione S-transferase and the risk of acute myeloid leukemia in a Saudi population

Objective

This study aims to investigate the genetic association of acute myeloid leukemia and glutathione S-transferase (GST) gene polymorphisms in a Saudi population.

Method

100 AML cases and 100 healthy controls were recruited from the Riyadh regional hospital. In the GST gene, GSTM1 and GSTT1 variants were genotyped by multiplex PCR, and GSTP1 variants were genotyped by PCR-RFLP analysis. Statistical analysis between AML cases and controls included anthropometric measurements and evaluation of the genotypic and allelic frequencies.

Result

The null genotypes of GSTM1 and GSTT1 showed no association with AML [OR 0.56 (0.26–1.19); p = 0.31 and OR 0.65 (0.37–1.16); p = 0.14]. Similarly, the GSTP1 genotype and allele frequencies did not indicate any association with AML [GG + AG vs. AA: OR 0.75 (0.43–1.31) and p = 0.32; GG vs. AA: OR 1.73 (0.55–5.44) and p = 0.34; G vs. A: OR 0.95 (0.61–1.46) and p = 0.82]. Further, a haplotype analysis between AML cases and controls did not show any positive association (p < 0.05).

Conclusion

In conclusion, there was no statistical association of the genotypes and alleles in GSTM1, GSTT1, and GSTP1 with AML. Our results confirm the negative association of the investigated genetic markers with susceptibility to AML. Further association studies would be required in different ethnic populations to facilitate a meta-analysis in the future. Our findings suggest that the GST gene has no role in the pathogenesis of AML in patients from Saudi Arabia.

Glutathione S-Transferase M1 and T1 Gene Deletions and Susceptibility to Acute Lymphoblastic Leukemia (ALL) in adults

Objective:

Biotransformation of xenobiotics are critical for their metabolism and removal from the body which is carried out by xenobiotic metabolizing enzymes. Individuals carrying variants of genes that encode these enzymes have an altered ability to metabolize xenobiotics which may lead to an increased risk of acute lymphoblastic leukemia. The current study aimed to investigate the impact of GSTM1 and GSTT1 gene deletions in causing predisposition to adult ALL.

Methods:

The current case-control study involved 62 adult ALL patients and 62 age and gender matched healthy controls. Whole blood samples processed with standard phenol chloroform protocol for DNA isolation were genotyped using multiplex PCR approach for simultaneous identification of GSTM1 and GSTT1 deletions. The genotype frequency obtained for patients was compared to controls using odds ratio and chi-square.

Results:

The null genotype frequency of GSTM1 and GSTT1 in a group of adult ALL patients from Pakistan were 47% and 11% respectively. Deletion of GSTM1 and GSTT1 did not show statistically significant association with adult ALL (p=0.86 and p=0.35 respectively). The combined GSTM1/GSTT1 deletion was observed in 2% patients and was not significantly associated with ALL in adults (p=0.85).

Conclusions:

The results reveal that homozygous null polymorphism of GSTM1 and GSTT1genes does not influence ALL susceptibility among adult patients. Cancer susceptibility associated with GST polymorphism varies with ethnic and geographic differences. Therefore, further investigation on different populations is needed to understand the role of these genetic variations in modifying adult ALL risk.