TCF7L2 and colorectal carcinoma: Considering the importance and functional contribution of the G-subunits genes in CRC progression, GNAS gene is among the top seven most frequently recognized mutated genes in tumourigenesis, such as in CRC; others include APC, KRAS, TCF7L2, epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGF1R) and CASP8 [2].