ATM and Ataxia: The DDR pathways regulated by shelterin includes ATM (Ataxia Telangiectasia Mutated), ATR (Ataxia Telangiectasia and Rad3-related), Non-Homologous End Joining (NHEJ), Homologous Recombination (HR), and Alternative Lengthening of Telomeres (ALT) [24].