RBBP8 and Jawad syndrome: Human CtIP, which is mutated in Seckel2 and Jawad syndromes (Qvist et al., 2011), has been shown to be crucial for the promotion of end resection and HR-mediated repair in many genetic studies (Huertas and Jackson, 2009; Sartori et al., 2007; You et al., 2009), but exactly how MRN and CtIP co-operate to achieve short-range resection is not fully understood.