Furthermore, evidence for loss of function of ATM was detected in three different AD transgenic mouse models; R1.40, which expresses a single (full-length) APP transgene, PS/APP, expressing transgenes for both APP and presenilin-1 (PSEN1) and triple-transgenic animals (3xTg), which bear APP, PSEN1, and MAPT transgenes, together implying that defective repair of DSBs is present in AD (Shen et al., 2016). Here, PSEN1 is linked to Alzheimer disease.