However, no loss of the second FLCN allele was present in these tumors, and the FLCN mutations were suggested likely passenger variants caused by the MSI [26] or acting by a dominant negative effect [19], while a somatic second hit with loss of heterozygosity was detected in a patient with a germline FLCN c.1177-5_1177-3del mutation, implicating FLCN as an initiating factor in tumorigenesis in CRC [10]. The gene discussed is FLCN; the disease is colorectal carcinoma.