The ATRIP-ATR signalling complex is a central mediator of the replicative stress response (RSR) (Saldivar et al., 2017), and mutations in both genes have been reported in Seckel syndrome (Mokrani-Benhelli et al., 2013; O'Driscoll et al., 2003; Ogi et al., 2012). Here, ATR is linked to microcephalic primordial dwarfism.