The authors describe the first case of a juvenile form of neural ceroid-lipofuscinosis in the Czech Republic. The patient had a typical initial symptom of progressive impaired vision which developed during preschool age. This disorder was soon followed by behavioural disorders with signs of relatively rapidly progressing dementia. From the age of nine years the boy had generalized epileptic attacks. From the age of 15 years his mobility deteriorated rapidly and within one year with advancing spasticity the boy was completely immobile. The EEG tracing was grossly abnormal, finally with generalized epileptic activity. On the fundus severe pigmental degeneration of the retina and atrophy of both optic nerves was present. Photostimulation and electroretinographic responses could not be produced. Magnetic resonance of the brain revealed typical supratentorial atrophy with an altered signal in particular in the thalamic area. In bioptic material (skin) lysosomal accumulation with „finger print“ appearance was found as well as other membraneous formations, in particular of the rectilinear type. In the peripheral lymphocytes marked typical vacuolization was present. The diagnosis of the juvenile form of neuronal ceroid-lipofuscinosis was confirmed by the finding of a typical deletion mutation in the region of the NCL3 locus.

        Key words: neuronal ceroid-lipofuscinosis, juvenile form, lymphocytic vacuolization, deletion mutation