ARID1A and neoplasm: HGSC-1 harboured a stop-gain mutation in BRCA1 (p.L63*, pathogenic); CCC-1 had a frameshift mutation in ARID1A (p.P1995Lfs*22, p.Q1098Rfs*16); EM-1 had a frameshift mutation (p.K1072Nfs*21) and a stop-gain mutation (p.R1276*) in ARID1A; and EM-2 had a missense mutation in ARID1A (p.P251A) in both organoids and tumours.