In the CNS, p16 expression increases during natural aging and in brains affected by pathologies such as Parkinson's disease (PD), multiple sclerosis (MS), and Alzheimer's disease (AD) (Martin‐Ruiz et al., 2020; Nicaiseet al., 2019; Zhang et al., 2019). The gene discussed is CDKN2A; the disease is Parkinson disease.