ATR and Fanconi anemia: Besides, some other core components of HR such as RAD51 recombinase (RAD51), ATM serine/threonine kinase (ATM), ATR serine/threonine kinase (ATR), partner and localizer of BRCA2 (PALB2), and Fanconi anemia gene family are determinants of intact HR as well [40, 61].