SHMT1 and rectal carcinoma: SHMT-1 and SHMT-2 have been associated with a wide variety of human phenotypes, including neural tube defects (Duthie, 2011), childhood acute leukemia (Relton et al., 2004), rectal carcinoma (Vijayakrishnan & Houlston, 2010), and prostate cancer (Komlósi et al., 2010).