ATR and microcephalic primordial dwarfism: It is unlikely transformed cells can survive without MRE11A, RAD50, ATRIP or PALB2 although significantly reduced levels may be tolerated, as evidenced by the ATR expression in Seckel syndrome and hypomorphic MRE11A and RAD50 mutations in ATLD and NBS-like disorder patients, respectively [37, 38].