MTHFR and rectal cancer: The distribution of SHMT1 C1420T and MTHFR C677T genotypes in controls and cases was in conformity with the HWE (SHMT1: controls p = 0.131 and colon cancer p = 0.843; controls p = 0.167 and rectal cancer p = 0.973; MTHFR: controls p = 0.074 and colon cancer p = 0.063; controls p = 0.126 and rectal cancer p = 0.403).