br Conclusions In this study we report the genotype frequenc
Conclusions In this study, we report the genotype frequencies for GSTT1, GSTP1, and GSTM1 in Jamaican children. The frequency of the null genotypes of GSTT1 and GSTM1 are similar to those of African-Americans in the US. The GSTP1 genotype frequency is closer to that of the African-American population than that of other African populations. Although in univariable analyses we did not find any significant associations between ASD and the GSTP1, GSTT1, and GSTM1 mst2 individually, we found a significant interaction between GSTP1 and GSTT1 in relation to ASD. Specifically, for Jamaican children heterozygous for the GSTP1 Ile105Val polymorphism, those with the null genotype (i.e., DD) in GSTT1 have almost three times higher odds of ASD when compared to children with either the GSTT1 I/I or I/D genotype. Our findings suggest that interaction between GSTT1 and GSTP1 may influence individual susceptibility to ASD. Our findings reiterate that when searching for genetic risk factors related to ASD, simply checking for additive effects of individual genes could mask more complex interactive effects. In addition, our findings could help to identify a subgroup of children who may be at a higher risk of ASD based on their GSTP1 and GSTT1 genotypes. However, although this work may have the potential to lead to future applications in prevention and screening in a public health context, more studies confirming the observed gene–gene interaction are needed.
Acknowledgements This research is co-funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Institutes of Health Fogarty International Center (NIH-FIC) by a grant (R21HD057808) as well as National Institute of Environmental Health Sciences (NIEHS) by a grant (R01ES022165) awarded to University of Texas Health Science Center at Houston. We also acknowledge the support provided by the Biostatistics/Epidemiology/Research Design (BERD) component of the Center for Clinical and Translational Sciences (CCTS) for this project. CCTS is mainly funded by the NIH Centers for Translational Science Award (NIH CTSA) grant (UL1 RR024148), awarded to University of Texas Health Science Center at Houston in 2006 by the National Center for Research Resources (NCRR) and its renewal (UL1 TR000371) by the National Center for Advancing Translational Sciences (NCATS). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NICHD or the NIH-FIC or NIEHS or the NCRR or the NCATS. Finally, we acknowledge a special discount received from the Western Psychological Services (WPS) (Torrance, CA) for the purchase of ADOS, ADI-R, and SCQ forms that were used for this study.
Introduction GSTs (EC 126.96.36.199) are phase II metabolizing enzymes which catalyze the conjugation of a wide range of electrophilic compounds, including carcinogens, mutagens and anticancer drugs , , , , , , to the ubiquitous tripeptide glutathione (GSH). Therefore, GSTs play an important role in the protection of cells against the toxicity of xenobiotic compounds and lipid hydroperoxides generated by oxidative stress , . In leukemic lineages, studies of the expression and the activity of GST isoenzymes revealed that the human Pi class GST isoform (GSTP1-1) is the most represented, particularly in U937, K562 and Jurkat cells . GSTP1-1 is commonly increased in many tumors , , , ,  and involved in the development of antineoplastic drug resistance , , , . Interestingly, GSTP1-1 has been shown to be involved in preventing apoptosis in hematopoietic cells  and to protect against H2O2-induced cell death via the coordinated regulation of stress kinases . On the other hand, the gene expression of inflammatory and immune responses , ,  as well as antioxidant enzyme genes such as GSTs ,  are enhanced in oxidative stress conditions. However, molecular mechanisms of the GSTP1-1 gene regulation are poorly understood. It has been shown that the region between −80 and −8 is necessary for constitutive expression of the gene  and the organization of a minimal promoter has been described . As shown in Fig. 1, cis-acting elements were identified within the minimal promoter . The role of the activator protein 1 (AP-1) binding site −69/−63 has been shown in the regulation of the GSTP1-1 gene expression, notably in VCREMS breast cancer cells . In addition, we have demonstrated by promoter deletion analyzes that this site was crucial for 12-O-tetradecanoyl phorbol 13-acetate (TPA)-mediated GSTP1 gene transcription . Two Sp1 response elements were also identified  as well as a NF-κB like sequence , .