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

Objective: Biotransformation of xenobiotics is 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 GSTT1 genes 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.