Infantile neuronal ceroid lipofuscinosis: The first reported case in Japan diagnosed by palmitoyl-protein thioesterase enzyme activity deficiency

We herein report on a Japanese boy with infantile neuronal ceroid lipofuscinosis (INCL). He was born of incest to a girl and her maternal uncle. His development was normal at 12 months, and began to display regression at 14 months. He lost his social smile and tracking eye movement at 16 months, and could not stand and developed severe hypotonic tetraplegia at 19 months. Myoclonic movement was observed in his trunk, eye and extremities. His height, body weight and head circumstance had been normal. Both MRI and CT scans of his head showed severe cerebral, cerebellar and brainstem atrophy. The electroretinogram showed a decrease in amplitude. Enzyme studies revealed a deficiency of palmitoyl-protein thioesterase activity in his lymphocytes at 0.98 nmol/h/mg protein (control: 90.99 ± 34.23). This is the first case of INCL in Japan diagnosed by enzyme activity deficiency.