PPT1 and infantile neuronal ceroid lipofuscinosis: INCL, the most severe form, results from defects in the protein Palmitoyl Protein Thioesterase 1 (PPT1) which encodes a lysosomal thioesterase that cleaves long fatty acids-most likely palmitate-attached to the cysteine residues of S-acylated protein substrates [3], [4].