PARP-1 activation also occurs in neurodegenerative DNA repair disorders including xeroderma pigmentosum group A (XPA) and Cockayne syndrome group B (CSB), and treatment with specific PARP inhibitors rescues defective phenotypes in XPA mutant worms and CSB mutant mice respectively [39, 94]. This evidence concerns the gene PARP1 and xeroderma pigmentosum.