ARH3 has specificity for bothpoly-ADP-ribose chains as well as mono-ADP-ribose moieties attached to serines(Abplanalp et al.,2017; Fontana etal., 2017), whereas TARG hydrolyses the ester linkagebetween mono-ADP-ribose and aspartate or glutamate side chains (Sharifi et al., 2013).ARH3 mutations are associated with neurodegenerative defects such as ataxia andfebrile seizures, while TARG1 loss causes severe developmental delay, epilepsyand quadriplegia (Sharifi etal., 2013; Danhauseret al., 2018; Ghosh et al., 2018). Here, ADPRS is linked to cerebellar ataxia.