In conclusion, this study as well as our previous genetic studies on MTHFR in breast and prostate cancer [7, 44, 45], EGFR in lung cancer [46], and GPX-1 in bladder cancer [47] is an important contribution in order to integrate pharmacogenetics in clinical practice in Ecuador and Latin America [48, 49]. Here, MTHFR is linked to urinary bladder carcinoma.