Clinical and electrophysiological features of epilepsy in Italian patients with CLN8 mutations

Neuronal ceroid lipofuscinoses (NCLs) are characterized by epilepsy, visual failure, psychomotor deterioration, and accumulation of autofluorescent lipopigment. CLN8 mutations result in Northern epilepsy and Turkish variant late infantile NCL. We describe the clinical and neurophysiological findings of three patients with CLN8 mutations from Italy. In these patients, the onset of epilepsy occurred between 3 and 6 years of age, with myoclonic, tonic-clonic, and atypical absence seizures. Electroencephalograms revealed focal and/or generalized abnormalities. In all cases, blindness and progressive attenuation of the electroretinogram were observed. Magnetic resonance imaging revealed cerebral and cerebellar atrophy, thinning of the corpus callosum, deep white matter hyperintensity, and hyperintensity of the posterior limb of internal capsules. Skin biopsy revealed lysosomal storage in the cytoplasm of fibroblasts. The clinical picture of our cases resembles that of the Turkish patients and clearly differs from that of Northern epilepsy, which is marked by a prolonged course without myoclonus and visual loss. Definition of the clinical spectrum of this condition will aid in its recognition and have implications for diagnosis and genetic counseling.