MUC1 and sclerosing cholangitis: When stratifying patients according to clinical features, we observed a particularly high mutation burden of 181 small somatic variants (SNVs/indels; average among 37 iCCA patients was 74), including two missense mutations in MUC1 and frameshift mutations in ELF3 and AURKAIP1, in‐patient CCC‐036 with primary sclerosing cholangitis (Table S1).