Large polyspikes in the EEG associated with flash stimulation at slow rates have been described as a characteristic of LINCL [47] and other studies have reported PPR in 9/13 (69%) CLN2 patients at a median of 48 m [44] and estimated 60% of CLN2 patients show PPR [48]. This evidence concerns the gene TPP1 and late infantile neuronal ceroid lipofuscinosis.