PROJECT ABSTRACT Focal epilepsy is the most common form of refractory epilepsy. Focal seizures are often associated with malformations of cortical development (MCD) but can also occur in the absence of a radiographically-detected lesion. Patients will often require surgical resection of the epileptogenic lesion to control their seizures, as many patients develop a drug resistance to the numerous antiepileptic drugs available. The availability of resected tissue has allowed for the study of the role of somatic variation in focal epilepsy. Somatic variation arising during embryonic brain development is increasingly recognized as a major contributor to genetic risk of focal epilepsy. Somatic variants localized to the brain have been readily identified in hemimegalencephaly and focal cortical dysplasia (FCD) type II; furthermore, evidence suggests that somatic variants also contribute to FCD type I and radiographically nonlesional focal epilepsy. While there has been substantial progress in our understanding of the genetic architecture underlying focal epilepsy, more work is needed to characterize the remaining cases lacking a genetic cause. Continued work to identify novel genes and the types of variants involved in focal epilepsy is essential to further advance understanding of the underlying mechanisms of disease and fuel the development of novel therapeutic approaches. The overall goal of my dissertation and postdoctoral research is to advance novel gene discovery in focal epilepsy and identify pathways that cause focal seizures to better inform drug discovery strategies and widen the scope of treatment. I have demonstrated my ability to identify putative pathogenic somatic variation affecting known epilepsy genes, as shown in my preliminary data in Aim 1. I have also identified a disease-causing variant in genes not yet associated with focal epilepsy. In Aim 1, I propose using deep exome and targeted sequencing approaches to identify novel genes and variants contributing to intractable focal epilepsy. Additionally, I propose using duplex sequencing to detect low abundance somatic variants that may have been missed by exome and panel sequencing. In the K00 Phase, I plan to expand these studies to in vivo models to probe the functional consequence of pathogenic somatic variation in the zebrafish model system. The proposed research provides opportunities for developing technical expertise in gene discovery, functional characterization of disease-causing somatic variation and drug discovery. I will rely heavily on the support of my sponsors to contribute to the development of my skillset in experimental design, scientific communication, and grantsmanship; as well as advancing my search for a postdoctoral training environment that is aligned with my research interests and career goals. The training plan outlined in this proposal integrates scientific and professional development that will put me on a trajectory to emerge as a well-rounded and indepen...