In addition to breast cancer susceptible gene (BRCA) deficiency, heightened sensitivity to PARP inhibition has also been observed in cells with other genetic lesions that affect HR, including phosphatase and tensin homolog (PTEN) deficiency, ataxia telangiectasia mutated (ATM) deficiency, and Aurora A overexpression14–16. The gene discussed is PARP1; the disease is breast carcinoma.