For logistical reasons we opted to obtain proof of concept data in Ppt1−/− mice (CLN1 disease), rather than either Cln2R207X mice (CLN2 disease) that have a severe and fatal seizure phenotype29 or Cln3Δex7/8 mice (CLN3 disease) that have a normal lifespan40. Here, TPP1 is linked to glycogen storage disease VI.