The hypermutated type with MSI/mismatch repair deficiency (MMRd) group, linked to an intermediate prognosis, exhibited mutations in TP53, FBXW7, CTNNB1, ARID1A, PIK13CA, PIK3RI, PTEN, RPL22, PTEN, KRAS, ATR, CHK1, CDC5, Caspase 5, the BAX gene, and JAK1, which are prevalent in endometrioid EC [54,55,56]. This evidence concerns the gene CHEK1 and mismatch repair cancer syndrome 1.