Genetic Diagnosis and Personalized Medicine for Patients With Epilepsy

Background Epilepsy is a common neurological disorder. It affects 50 million people worldwide and has the highest incidence in pediatric age. According to the latest classification of the ILAE (International League against Epilepsy), epilepsies are divided into lesional (symptomatic) and non-lesional/genetic forms. Symptomatic causes of epilepsy may include scarring, tumors, strokes, and brain developmental disorders such as dysplasias. In approximately 30% of epilepsies a genetic cause of epilepsy can be hypothesized. Since the identification of the first epilepsy gene in 1995, over the next 25 years over 500 genes associated with epilepsy have been identified. The importance of many genes and many gene variants identified in many genes is not yet clear and the mutations identified in different genes require confirmation with functional studies and confirmation on larger series of patients. Furthermore, the genetic defect underlying many patients with epilepsy remains unknown to this day, despite a high level of gene sequencing effort. Molecular studies on these genes have demonstrated how pathogenic variants on these genes determine a protein dysfunction that can cause neuronal hyperexcitability and pathological synchronization of neuronal networks leading to epileptic seizures and brain dysfunction. A notable complication in the field of epilepsy genetics is represented by the fact that the concept of a gene/a disease is valid only in a few cases, as there is a high phenotypic and genotypic heterogeneity so that a gene can present different types of epilepsy even within the same family. This means that there is a complex multigenic and multifactorial genetic substrate for which the impact of a specific genetic variant is conditioned by variants of other genes. This concept is particularly valid for the most common epileptic forms such as idiopathic generalized epilepsies. The integration of genetic analysis with epileptological characterization in clinical prac