Northern epilepsy is a genetically determined disease, previously diagnosed only in people from Finland. A characteristic feature of the disease is that, in addition to convulsive seizures, patients also experience significant intellectual disorders. There is simply no cure for northern epilepsy - so how does this disease affect the lives of people suffering from it?

Northern epilepsy(Northern epilepsy, also known as progressive epilepsy with mental retardation) is quite an unusual disease - it is found only in people from Finland. The Finnish population is generally quite specific, which is due to, inter alia, due to the fact that in the history of this population there has been often its isolation, as well as a significant decrease in the number of inhabitants in this region of the world. In such conditions, there may be the so-called founder effect associated with the fact that in a given population there is a reduction in the genetic pool. The consequence of this phenomenon may be an increase in the frequency of various diseases caused by genetic mutations, including northern epilepsy. Apart from this disease, there are over 30 other genetic diseases, which occur much more often in the Finnish population than in other ethnic groups. It should also be emphasized that other, quite common genetic diseases, such as phenylketonuria or cystic fibrosis in Finns, are generally not observed.

Northern epilepsy is considered a variant of neuronal ceroid lipofuscinosis and it is quite rare - the disease affects an estimated 1 in 10,000 people from the northern region of Finland. Both women and men can suffer from this disease. Northern epilepsy was described quite recently (the first publication on this disease appeared in 1994), and it was written by a team led by A. Hirvasniemi.

Northern epilepsy: causes

Northern epilepsy is caused by a mutation of the gene encoding the CLN8 protein, located on the short arm of chromosome 8. The condition is inherited in an autosomal recessive manner, which means that you need two copies of the mutated gene to get the disease. It is also possible to be a carrier of a mutation. It is found in about 1 in 135 Finns,carriage, however, does not lead to any deviations in a given person. However, it is related to the possibility of transmitting the mutation to the offspring - if both parents are carriers of the CLN8 gene mutation, the risk that their offspring will develop progressive epilepsy with mental retardation in each pregnancy of such a couple is 25%.

The function of the CLN8 protein - both normal and pathological - is not known so far. This protein probably corresponds to, among others for regulating the transport of various substances to one of the cell organelles - the endoplasmic reticulum. Ultimately, the mutation results in an increase in the death of nerve cells and the deposition of various substances in the brain of patients - mainly proteins.

Northern epilepsy: symptoms

The course of northern epilepsy is variable - the clinical picture changes with the patient's age. The first symptoms of the disease appear early, around 5-10. age. In the beginning, patients with progressive epilepsy with mental retardation develop repeated episodes of seizures. They usually take the form of tonic-clonic seizures, during which loss of consciousness, a significant increase in muscle tone and convulsions can be observed. Partial seizures are also possible. During this period of the disease, epileptic seizures appear about 1-2 times a month, their duration usually does not exceed 15 minutes. A characteristic feature of northern epilepsy is that when a patient begins to experience epileptic seizures, he also develops intellectual disorders, consisting in a significant deterioration in mental functions.

Northern epilepsy becomes worse when a patient suffering from this disease begins to mature. It is during this period of life that the frequency of seizures increases to 1-2 times a week. Intellectual disorders are also becoming more and more pronounced - patients may experience impaired motor coordination or the inability to acquire knowledge. In rare cases, patients also develop various visual disturbances (usually consisting of blindness).

The period of adulthood is theoretically the time when the course of progressive epilepsy with mental retardation alleviates. In adulthood, patients suffering from northern epilepsy experience epileptic seizures much less frequently, about 4 to 6 times a year. This period of the disease is only seemingly the mildest, because it is then that intellectual deficits are so significant that patients become incapable of completely independent existence.

Northern epilepsy: diagnosis

Due to the etiology of the disease, the diagnosis of epilepsy with progressive mental retardation is based on genetic tests. It is thanks to molecular tests that it becomes possible to confirm the existence of the CLN8 gene mutation in the patient, which is responsible for the occurrence of northern epilepsy. Electroencephalography (EEG) and imaging tests (such as magnetic resonance imaging of the head) may also play a helpful role in diagnosing the disease. Conducting numerous and diverse studies is mainly used to differentiate northern epilepsy from other entities, such as, for example, chronic encephalitis or mitochondrial diseases.

Northern epilepsy can be diagnosed even before human birth - genetic prenatal tests can be used for this purpose. Genetic counseling is also available, especially for those in whom the condition has already been diagnosed in a family member. Genetic counseling may be based on deleting a pedigree, but also on determining what and whether there is a risk of possible transmission of the disease to offspring.

Northern epilepsy: treatment

Currently, northern epilepsy is an incurable disease - medicine does not know the methods by which it would be possible to correct the genetic mutations existing in patients with this entity. In the treatment of patients with this disease, only symptomatic treatment is used to alleviate the symptoms experienced by them. In this case, medical interventions focus on administering medications that depress the functioning of the nervous system, preparations used for this purpose include benzodiazepines (such as clonazepam) or s alts of valproic acid. Pharmacotherapy for northern epilepsy is especially useful for patients in adolescence, when they have the most seizures; the frequency of seizures associated with the condition can be reduced by medication, and the bad news is that there are no methods to slow the deterioration of intellectual function. in patients with northern epilepsy.

Northern epilepsy: prognosis

Northern epilepsy is a progressive disease, however, the progression of the disease is rather slow. Despite this, the condition unfortunately leads to the premature death of those suffering from it - the life expectancy for progressive epilepsy with mental retardation is around 50-60 years.

Category:

Genetic diseases