Epilepsy is one of the most common neurological disorders, with a prevalence ~1%. The Early Infantile Epileptic Encephalopathy (EIEE) includes a wide range of epilepsys starting before 3 years of life and generating also a developmental delay. Next Generation Sequencing technologies (NGS) have allowed to improve the diagnostic of many patients, finding new mutations responsible for this disease. Those tools showed that EIEE is caused by several genetic variants placed in different genes. However, it is known that an important percentage of epileptic phenotipes (30 - 90%) can not be genetically classified using classic approaches; that means that most of the molecular architecture of the disease is still unknown. Structural variants (SV) are involved in many complex disease as autism, mental disorders or cancer, but they have been little studied in rare diseases. The aim of this project is to explore the potential of structural variants in EIEE pathogenesis using Whole Genome Sequencing.