We present compelling evidence implicating LY6E (lymphocyte antigen 6 complex, locus E; aliases RIGE; SCA2; RIG-E; SCA-2; TSA-1), a member of the Ly-6/uPAR protein family and is a critical mediator of PARPi resistance in BRCA1-deficient ovarian cancer. This evidence concerns the gene BRCA1 and ovarian cancer.