The developments in molecular studies have also helped to define the molecular basis of type I ovarian cancers, including LGS-OvCa characterized by frequent BRAF, KRS, PTEN and PIK3CA gene alterations, Ovarian Clear Cell Carcinoma characterized by frequent ARID1A and PIK3CA gene alterations, Endometrioid Ovarian Cancers characterized by frequent ARID1A, PTEN, CTNNB1 and PI3KCA gene alterations and Mucinous Ovarian Carcinomas characterized by frequent KRAS, TP53 and CDKN2A gene alterations. This evidence concerns the gene ARID1A and ovarian mucinous adenocarcinoma.