Neuronal ceroid lipofuscinoses (NCLs) are the most common group of neurodegenerative diseases that presents in childhood and are characterized by seizures and progressive neurological deterioration, which results in dementia, ataxia, visual failure, and various forms of abnormal movement. The most common form of neuronal ceroid lipofuscinoses is late infantile (LI-NCL), in association with the genes CLN2, CLN5, CLN6, and CLN8. We report the cases of neuronal ceroid lipofuscinoses type 8 in 3 patients from 2 unrelated families, which was confirmed by molecular testing in 2 of them. Multiple spontaneous abortions, early death, and early onset of motor disability were observed in our cases, reflecting a possible association of NCL 8 with other unrecognized neurodegenerative diseases. Our results expand the genotypic/phenotypic background of variant late Infantile-NCL in Arabic ethnicity.

CLN8 disease is one of the thirteen recognized genetic types of neuronal ceroid lipofuscinosis, a group of neurodegenerative lysosomal storage disorders, most frequent in childhood. A putative 286 amino acids transmembrane CLN8 protein with unknown function is affected. Pathological variants in the CLN8 gene were associated with two different phenotypes: variant late-infantile in individuals from many countries worldwide, and epilepsy progressive with mental retardation, appearing in Finnish and Turkish subjects. The girl showed psychomotor delay and dementia since birth, tonic-clonic seizures, myoclonus, ataxia with cerebellar atrophy, and early death at 12 years old. Electron microscopy of the skin showed mixed GROD, curvilinear, fingerprint cytosomes and mitochondrial hypertrophy. Two pathological DNA variants in the CLN8 gene (exon 2 c.1A>G; p.?/ exon 3 c.792C>G; p.Asn264Lys) were found confirming a compound heterozygous genotype. This case is the Latin American index for a new congenital phenotype of the CLN8 disease. The congenital phenotype has to be added to the clinical spectrum of the CLN8 disease. The suspicion of CLN8 disease should be genetically sustained in challenging cases of a neurodegenerative syndrome with psychomotor delay since birth, speech difficulty and seizures. The course includes ataxia, cerebellar atrophy, and early death. Enfermedad CLN8 congenita de lipofuscinosis neuronal ceroidea: un nuevo fenotipo. Introduccion. La enfermedad CLN8 es uno de los 13 tipos geneticos reconocidos de lipofuscinosis neuronal ceroidea, un grupo de trastornos neurodegenerativos de acumulacion lisosomica, los mas frecuentes en la infancia. La causan mutaciones en la proteina transmembrana CLN8 de 286 aminoacidos, cuya funcion se desconoce. Las variantes patologicas en el gen CLN8 se asociaron con dos fenotipos diferentes: la variante infantil tardia en individuos de diversos paises alrededor del mundo, y la epilepsia progresiva con retraso mental, que aparece en pacientes finlandeses y turcos. Caso clinico. Niña que mostro retraso psicomotor y demencia desde el nacimiento, convulsiones tonicoclonicas, mioclonia, ataxia con atrofia cerebelosa y muerte temprana a los 12 años. La microscopia electronica de la piel mostro una mezcla de citosomas con patrones de depositos osmiofilicos granulares, curvilineos y de «huella digital», y mitocondrias hipertrofiadas. Se encontraron dos variantes patologicas de ADN en el gen CLN8 (exon 2 c.1A>G; p.?/ exon 3 c.792C>G; p.Asn264Lys), lo que confirmo un genotipo heterocigoto compuesto. Conclusion. Este es el caso indice en America Latina para el nuevo fenotipo congenito de la enfermedad CLN8. La sospecha de esta patologia deberia sustentarse geneticamente en casos de sindrome neurodegenerativo con retraso psicomotor desde el nacimiento, dificultad del habla y convulsiones. El curso clinico incluye ataxia, atrofia cerebelosa y muerte temprana.

Neuronal ceroid lipofuscinosis (NCL), one of the most common neurodegenerative childhood-onset disorders, is characterized by autosomal-recessive inheritance, epileptic seizures, progressive psychomotor deterioration, visual impairment, and premature death. Based on the country of origin of the patients, the clinical features/courses, and the molecular genetics background of the disorder, 14 distinct NCL subtypes have been described to date. CLN8 mutation was first identified in Finnish patients, and the condition was named Northern Epilepsy (NE); however, the severe phenotype of the CLN8 gene was subsequently found outside Finland and named 'variant late-infantile' NCL. In this study, five patients and their six healthy relatives from a large Turkish consanguineous family were enrolled. The study involved detailed clinical, radiological and molecular genetic evaluations. Whole-exome sequencing and homozygosity mapping revealed a novel homozygous CLN8 mutation, c.677T>C (p.Leu226Pro). We defined NE cases in Turkey, caused by a novel mutation in CLN8. WES can be an important diagnostic method in rare cases with atypical courses.