According to IHC and next–generation sequencing (NGS) technology, EOVC is divided into the following four groups (96): TP53 wild-type (TP53wt) group with no obvious abnormalities, which accounts for the largest proportion (51.2~73.2%) of EOVC, followed by TP53 abnormal (TP53abn) group (9.6~24%), MMR protein deficiency (MMRd) group (8.3~19.4%), and the POLE hyper mutant (POLEmut) group (2.8~10%) (95, 96) (Figure 2). Here, TP53 is linked to protein S deficiency.