Mutations in CLN1, coding for the Palmitoyl-Protein Thioesterase 1 (PPT1) enzyme, are associated with CLN1 disease (OMIM #256730), a progressive, neurodegenerative disorder of childhood, characterized by acquired microcephaly, hypotonia, delayed psychomotor development followed by deterioration, untreatable seizures and myoclonus, truncal ataxia, and involuntary movements. The gene discussed is PPT1; the disease is microcephaly.