Focal cortical dysplasia (FCD) is a malformation of brain development, the most common cause of drug-resistant epilepsy and often caused by mutations in mammalian target of rapamycin (mTOR) pathway genes. Patients with FCD develop drug-resistant seizures. This study will look at FCD tissue removed during epilepsy surgery and aims to detect mutations in mTOR pathway genes in brain cells. Secondly, the investigators will establish if evidence of mutations found in brain cells can also be detected as circulating free DNA (cfDNA) in blood. By looking at which genes are made into proteins in individual cells found in epilepsy surgical tissue (single cell expression profiling),the investigators will attempt to identify new genetic targets in FCD. The main outcome will be finding new causes of epilepsy with FCD and the development of new diagnostic and screening tools.