JNCL is caused by mutations in CLN3, a gene involved in the regulation of lysosomal homoeostasis27, 28, 29, and is characterized by autophagic impairment and intralysosomal accumulation of ceroid lipopigment, which is detectable by confocal and electron microscopy30, 31. This evidence concerns the gene CLN3 and juvenile neuronal ceroid lipofuscinosis.