CLN3 and juvenile neuronal ceroid lipofuscinosis: On the other hand, we focused on juvenile neuronal ceroid lipofuscinosis (JNCL) or Batten disease, caused by mutations in CLN3, an LSD which shows prominent retinal and neurodegenerative phenotypes with gradual vision loss and progressive cognitive decline as observed in MLIV, and with a similar age‐dependent disease onset and evidence for disturbed lysosomal Ca2+ homeostasis (Chandrachud et al, 2015).