ERCC4 and Lynch syndrome: Our study is the first to report germline mutations in ERCC4. Moreover, previous research found that 7–8.3% unselected UTUC patients had Lynch syndrome-related features, such as deficient mismatch repair (dMMR), microsatellite instability high (MSI-H) or deleterious alterations of MMR genes, while only 2.1% occurred in UC patients [22, 25].