PARP1 and hypoparathyroidism-retardation-dysmorphism syndrome: In addition to monotherapy for cancers with HRD, PARP inhibitors are under clinical assessment in combination with other antitumor agents referred for chemotherapy, targeted therapy, and immunotherapy (Plummer et al., 2013; Norris et al., 2014; Matulonis and Monk, 2017; Tomao et al., 2017; Friedlander et al., 2019; Lee and Konstantinopoulos, 2019; Lampert et al., 2020; Palaia et al., 2020; Bizzaro et al., 2021; Waddington et al., 2021).