ATM and pachyonychia congenita: The identification of damaging mutations in DDR system genes, including ATM, in 17–25% of this type of cancer and the recent suggestion that PARP inhibitors could have therapeutic potential in cancers with loss or mutation of ATM are opening up the possibility of new therapies, such as platinum and more recently PARP inhibitors, also in ATM-mutated patients with PC [83,84,85].