For example, synthetic lethality with PARPi has been reported upon loss of Histone PARylation Factor 1 (HPF1) (10), defects in the ribonucleotide excision repair pathway (11), impairments of resolving trapped PARP1 (12–15) and loss of factors of the Fanconi anemia pathway (16). Here, HPF1 is linked to Fanconi anemia.