PPT1 is encoded by CLN1, and mutations in this gene are associated with a severe neurodegenerative disorder known as infantile neuronal ceroid lipofuscinosis (INCL, also known as Batten disease) (Santavuori et al., 1973; Weleber, 1998, 2004; Jalanko and Braulke, 2009). Here, PPT1 is linked to juvenile neuronal ceroid lipofuscinosis.