To examine the genetic dependencies of FAM126A and FAM126B, we identified sgRNAs that could efficiently deplete FAM126A and FAM126B (Figures 1F and S1B) and then used a competitive cell growth assay to measure the fitness effect following genetic deletion of FAM126A or FAM126B. CRC cells stably expressing Cas9 were infected with lentivirus co-expressing an sgRNA and a green fluorescent protein (GFP). The gene discussed is HYCC2; the disease is colorectal carcinoma.