Moreover, mutations in ATR are also associated with additional conditions including: ataxia, telangiectasia, mental disabilities, and overall nervous system defects, all of which occur in tissues that are not considered highly proliferative, which seems paradoxical to the established role of ATR as a cell cycle checkpoint protein [13,21,22,23,24,25,26,27,28]. This evidence concerns the gene ATR and Telangiectasia.