ATR and Fanconi anemia: Other HR pathway alterations include medium penetrance mutations in several Fanconi anemia genes (mainly PALB2 and Fanconi anemia complementation group A, C, I, and L (FANCA, -C, -I, and -L), in RAD genes (such as RAD50, RAD51 homolog 1 (RAD51), RAD51C, RAD51D and RAD54-like (RAD54L)), and in DDR genes involved in HR (ATM, Ataxia telangiectasia and RAD3 related (ATR), checkpoint kinase 1 (CHEK1), and CHEK2) [43].