Mutations in the CLN8 gene underlie Northern epilepsy (progressive epilepsy with mental retardation [EPMR], OMIM 600143) and a subset of Turkish variant late infantile NCL, but the pathogenetic mechanisms have remained elusive.
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.
EPMR patients were homozygous for a missense mutation (70C-->G, R24G) that was not found in homozygosity in 433 controls.We also cloned the mouse Cln8 sequence.
EPMR patients were homozygous for a missense mutation (70C-->G, R24G) that was not found in homozygosity in 433 controls.We also cloned the mouse Cln8 sequence.
In the remaining families, four CLN8 gene mutations were identified indicating that in a subset of patients with Turkish vLINCL, the disorder is allelic to Northern epilepsy.
We recently performed whole-exome sequencing in two families with affected siblings and then carried out a follow-up study and identified ceroid-lipofuscinosis neuronal 8 (epilepsy, progressive with mental retardation) (CLN8) as a potential genetic risk factor for ASD.
A missense mutation in CLN8 causes progressive epilepsy with mental retardation (EPMR) or Northern epilepsy, which has so far been reported only from Finland and is now classified as an NCL.