Data has emerged that a subset of individuals with Phelan-McDermid syndrome (PMS) experience devastating psychiatric symptoms, such as regression, bipolar disorder, and catatonia. The goal of this fellowship is to deeply characterize these psychiatric symptoms, refine guidelines, and/or explore their biological underpinnings. The fellow should have a clinical background in psychiatry or neurology and will work within the NIH-funded Developmental Synaptopathies Consortium (DSC), a Rare Disease Clinical Research Network. The training environment will include access to leaders in the field with a pre-established infrastructure for recruiting and phenotyping large numbers of individuals with Phelan-McDermid syndrome