Wang et al. recently stratified ovarian cancer into 7 subgroups within histotypes based on their diverse DNA repair deficiency-related signatures, which were characterized by mutation signatures associated with mismatch repair deficiency, the AID/APOBEC family of cytidine deaminases, age at diagnosis, the prevalence of foldback inversion structural variations, the prevalence of duplications or deletion rearrangements and homologous recombination deficiency. This evidence concerns the gene CDA and mismatch repair cancer syndrome 1.