Dr Marsh received his Medical Degree at New York University School of Medicine, as well as PhD in physiology and neuroscience at NYU Sackler School of Biomedical Sciences. He then completed his Internship and pediatric residency at NYU. He moved to CHOP for a Child Neurology residency where he stayed for fellowship in clinical neurophysiology and also completed a post doctoral fellowship, followed by being hired as faculty at Perelman School of medicine in the Departments of Neurology and Pediatrics. He is now an associate professor of neurology at University of Pennsylvania and CHOP and is board certified in Psychiatry and Neurology/Child Neurology. As a key member of the CHOP epilepsy program, and clinical director of the neurogenetics program, he has particular clinical interests in developmental epilepsies and cortical malformations. His research has focused strongly on the impact of intraneuronal development and altered excitability on epilepsy, as well as analyzing intracranial EEG recordings to better localize the epileptic zone and network. This work has primarily utilized a model of mutations in the gene ARX, but also performing basic science work with a number of other developmental genes including mouse work on Cdkl5. He has been involved in a number of clinical trials for children with the DEEs. He is actively involved in the Rett and Rett related (DEE) natural history studies and planning for future studies on the DEEs.