CHEK1 and Fanconi anemia: We first interrogated genes that have been described as synthetic lethal to PARP inhibition38, 42 and observed deleterious aberrations in multiple HRR components, including PTEN (57%), BRCA2 (53%), ATM (22%), CHEK1 (22%), XRCC3 (18%), CHEK2 (12%), BRCA1 (10%), and RAD51 (10%), as well as in members of the Fanconi anemia complementation groups, namely FANCA (27%) and FANCD2 (10%) (Fig. 7a).