Ovarian clear cell carcinoma (OCCC) is an aggressive ovarian cancer resistant to therapy. A study identified frequent mutations in the chromatin remodeling gene ARID1A in OCCC. Using exome sequencing of eight tumors, researchers found that 57% of 42 OCCC cases had ARID1A mutations, while 7% had PPP2R1A mutations. These mutations suggest ARID1A functions as a tumor suppressor gene, and PPP2R1A as an oncogene. PIK3CA and KRAS, previously implicated in OCCC, were also mutated. The study highlights the role of chromatin remodeling in OCCC pathogenesis and underscores the importance of specific mutations in cancer development. ARID1A mutations were found in both alleles in many cases, indicating inactivation of the gene. The study also shows that mutations in chromatin-modifying genes are characteristic of certain cancers, including OCCC. The findings emphasize the need to understand how chromatin modifications contribute to cancer progression and identify which epigenetic changes drive tumor growth. The study provides insights into the genetic basis of OCCC and the potential for targeted therapies.Ovarian clear cell carcinoma (OCCC) is an aggressive ovarian cancer resistant to therapy. A study identified frequent mutations in the chromatin remodeling gene ARID1A in OCCC. Using exome sequencing of eight tumors, researchers found that 57% of 42 OCCC cases had ARID1A mutations, while 7% had PPP2R1A mutations. These mutations suggest ARID1A functions as a tumor suppressor gene, and PPP2R1A as an oncogene. PIK3CA and KRAS, previously implicated in OCCC, were also mutated. The study highlights the role of chromatin remodeling in OCCC pathogenesis and underscores the importance of specific mutations in cancer development. ARID1A mutations were found in both alleles in many cases, indicating inactivation of the gene. The study also shows that mutations in chromatin-modifying genes are characteristic of certain cancers, including OCCC. The findings emphasize the need to understand how chromatin modifications contribute to cancer progression and identify which epigenetic changes drive tumor growth. The study provides insights into the genetic basis of OCCC and the potential for targeted therapies.