MRC1 and Lynch syndrome: Determining localized vs soma-wide mosaicism has important clinical implications; namely, (1) the risk of a second primary CRC for localized MMR mosaics could be mitigated by surgical removal of the affected part of the colon; (2) soma-wide MMR mosaics would have an increased risk of Lynch syndrome-related extracolonic cancers, whereas localized MMR mosaics would not; and (3) the MMR mosaic pathogenic variant would not be present in the primordial germ cells and, therefore, not heritable in localized MMR mosaic cases, whereas this would need to be established for the soma-wide cases.