An evaluation of the CRISPR preferentially essential genes and RNA-interference screening of colorectal cancer cell lines with the 20q11.21 amplification disclosed a few recurrent genes in more than one line, that include CTNNB1, encoding for β-catenin, the WNT pathway transcription factor TCF7L2 and oncogene KRAS (Table 6). The gene discussed is TCF7L2; the disease is colorectal cancer.