GSTA1 has 3 single nucleotide polymorphisms (SNPs): −567TOG, −69COT, and −52GOA.[101] Differential expression with lower transcriptional activation of variant GSTA1∗B (−567G, −69T, and −52A) than common GSTA1∗A allele (−567T, −69C, and −52G) are resulted from these replacements.[102] GSTM1 plays an important role in preventing the development of cancers. This evidence concerns the gene GSTM1 and cancer.