Lack of Participation of the GSTM1 Polymorphism in Cervical Cancer Development in Northeast Thailand

Glutathione S-transferases (GSTs) belong to a group of the phase II enzymes, which play roles in the detoxification of exogenous substrates (Schnakenberg et al 2000, Sanyal et al 2004). Among a variety of GST genes, an allele with a deletion of the whole GSTM1 gene (GSTM1Δ) was identified (Duell et al., 2002). Homozygous for the GSTM1Δ known as GSTM1-null resulting in the lack of enzyme activity has been investigated with a special reference to the susceptibility to various cancers such as oral cancer, nasopharyngeal carcinoma, lung cancer and others ( Schnakenberg et al., 2000; Tiwawech et al., 2005, Liu et al., 2014). However, the conventional PCR assay identifying the GSTM1-null (Δ/Δ) is unable to distinguish the heterozygous genotype (W/Δ) from the homozygous for the wild-type allele (W/W) and the susceptibility to cancers by genotype was unpredictable; in fact, risks for cancer development of the GTM1Δ are still unknown and related reports are also controversial (Singh et al., 2008; Matic et al., 2013; Safarinejad et al., 2013). In our previous study, we employed the conventional PCR to evaluate risk of the GSTM1-null for the squamous cell carcinoma of the cervix (SCCA) development in the northeast Thai women and found no relation between GSTM1-null and SCCA development (SettheethamIshida et al., 2009) however, presence of the genotype contribution could not be rejected. To make it clear whether