ARID1A and uterine carcinosarcoma: In contrast, the uterine carcinosarcoma was found to have pathogenic mutations in PIK3CA (c.1132T>C, p.C378R), TP53 (c.518T>G, p.V173G), ARID1A (c.2044_2047del, p.5682fs), KRAS (c.35G>C, p.G12A), with a copy number gain in MYCN.