Epilepsy North (Northern epilepsy) - Gen CLN8.  

North epilepsy is a genetic condition that causes epilepsy that begins in childhood, usually between 5 and 10 years old. This disease belongs to a group of disorders known as lipofuscinosis neuronal ceroid (NCL), or Batten disease. These alterations affect the nervous and causes progressive vision problems system, movement and mental concentration. Different types of NCL are distinguished by the age at which they first appear the signs and symptoms. Northern epilepsy is the mildest form of NCL.

Often seizures are generalized tonic-clonic, involving muscle stiffness, seizures and unconsciousness type. These episodes usually last less than 5 minutes, but can last up to 15 minutes. Some people with epilepsy North also manifested partial seizures, which do not lead to loss of consciousness. Seizures occur about once or twice a month until adolescence. Thereafter, the frequency is reduced to about four to six times a year in early adulthood. As the age of affected individuals progresses, the seizures become even less frequent.

Overall, between 2 and 5 years after the onset of seizures, affected people begin to show a decline in intellectual function, which can lead to a mild intellectual disability. In addition, problems with the overall coordination starting in adulthood and lead to clumsiness and difficulty in performing motor activities. Often during this time affected individuals begin to develop problems with balance and walking slowly with short and wide steps. These intellectuals and movement problems worsen over time. In addition, the early and middle adulthood these individuals may exhibit a decrease in visual acuity. People with epilepsy North live usually in late adulthood, but depending on the seriousness of the deficiencies of intellectual disability and movement, may need help with the tasks of daily life.

This process is due to mutations in the gene CLN8, located on the short arm of chromosome 8 (8p23). This gene encodes a protein whose exact function is unknown, but is believed to play a role in the transport inside the cells. Specifically, the protein CLN8 likely help transport materials within and outside the endoplasmic reticulum, involved in the production, processing and transport of proteins. Based on the structure of the protein CLN8, it may also be involved in regulating lipid levels in cells. Almost all people with epilepsy North have the same mutation in both copies of the gene in each cell CLN8. The responsible mutation, the amino acid arginine by replacing the amino acid glycine at position 26 in the CLN8 (Arg26Gly or R26G) protein. However, the effects of this mutation on protein function are unclear. Unlike other forms of NCL leading to the accumulation of large amounts of lipopigments in cells, Northern epilepsy is associated with very little accumulation of lipopigment. Affected individuals develop mild brain abnormalities as a result of cell death, but the cause of the death of brain cells is unknown. It is also unclear how changes in protein CLN8 and a loss of brain cells lead to neurological problems associated with epilepsy North.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with epilepsy North, by complete PCR amplification of the gene exons CLN8, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).