CDKN2A and Alzheimer disease: Increased levels of DNA damage checkpoints such as p53, p21 and p16, as well as SASP factors, have been observed in the spinal cord and brain of patients with amyotrophic lateral sclerosis (ALS) (De Felice et al. 2014) and Alzheimer's disease (AD) (Bhat et al. 2012), respectively.