ATM and hyperinsulinemic hypoglycemia, familial, 4: HyperPARylation and reduced NAD+ levels have been observed in rare diseases associated with impaired DNA repair, including WS (Fang et al. 2019), Cockayne syndrome (Scheibye‐Knudsen et al. 2014), ataxia telangiectasia mutated (ATM) deficiency (Fang et al. 2016), as well as neurodegenerative diseases such as Alzheimer's and Parkinson's disease (Lautrup et al. 2024).