Genomic Imprinting, Epigenetic Dysregulation, and Neuropsychiatric Mechanisms in Prader–Willi Syndrome: A Multi-Level Integrative Review

Prader–Willi syndrome (PWS) is a rare imprinting-related neurodevelopmental disorder caused by loss of paternally expressed genes within the chromosome 15q11–q13 region, including SNORD116, MAGEL2, and NDN. It provides a natural model for examining how genomic imprinting disruptions shape neural development and psychiatric vulnerability. This review synthesizes current evidence to clarify the mechanistic pathways linking imprinting defects and epigenetic dysregulation to neuropsychiatric outcomes in PWS. Published studies—including patient-derived induced pluripotent stem cell (iPSC) models, animal knockout systems (e.g., Magel2-null models), transcriptomic and DNA methylation datasets, and human neuroimaging research—were identified through targeted searches of PubMed and Web of Science and integrated narratively rather than through systematic procedures. Across these data sources, deletion-type PWS is primarily associated with impaired neuronal maturation, altered serotonergic signaling, and locus-specific transcriptional dysregulation. Maternal uniparental disomy (mUPD) is characterized by broader epigenetic alterations within the imprinted domain, genome-wide transcriptional effects, dopaminergic pathway alterations, and disrupted prefrontal–limbic connectivity linked to increased psychosis risk. Importantly, available evidence supports substantial phenotypic and mechanistic overlap between PWS subtypes, with genotype–phenotype associations reflecting probabilistic tendencies rather than categorical distinctions. Collectively, convergent findings across molecular, neurochemical, and systems-level studies support a mechanistic continuum extending from imprinting defects to behavioral phenotypes. These insights position PWS as a translational model for understanding how epigenetic dysregulation contributes to psychiatric risk and highlight the need for genotype-informed, mechanistically grounded research to advance biomarker development and targeted therapeutic strategies.