PPT1 and neuronal ceroid lipofuscinosis: For instance, a study by Sanders et al. identified a homozygous mutation c.736_737insC in exon 8 of PPT1 gene in a canine presenting NCL-like signs including, visual impairment, disorientation, behavioral changes, lack of PPT1 activity in the brain, and accumulation of autofluorescent lysosomal inclusions with the granular osmiophilic deposit in neurons [30].