Interestingly, three of these 4 genes are encoded by the X chromosome, TKTL-1, ZNF-711 and G6PD. TKTL1 has been correlated with worse outcomes in patients with invasive colon and urothelial tumors, oxygen-independent glucose usage and validated as a potential biomarker in breast cancer [37], [38]. This evidence concerns the gene G6PD and breast carcinoma.