ATR and microcephalic primordial dwarfism: In facts, loss-of-function mutations in different proteins implicated in DDR generate devastating neurological disorders besides A-T, such as ATR-Seckel syndrome, a complex pathology generated by mutations in ATR gene and characterized by microcephaly and progressive aging, LIG4 syndrome, ATLD (A-T-like disorder), and Nijmegen breakage syndrome [173].