Reversion mutations of HR genes may occur after prolonged exposure to PARPi and cisplatin; for example, the protein-truncating c.6174delT frameshift mutation of BRCA2 in cancer cells was converted to restore the open reading frame (ORF), thereby restoring function to the BRCA2 gene despite not having full conversion to the wild type gene [41]. The gene discussed is BRCA2; the disease is cancer.