BRCA1 and hypoparathyroidism-retardation-dysmorphism syndrome: RAD51C and PALB2 were recently linked to HRD as incidental cases using mutational signature-based approaches11,20 and our results now confirm that biallelic inactivation of these two genes results in HRD and is actually a common cause of HRD (albeit to a lesser extent than for BRCA1/2).