Single-cell RNA sequencing of brain tissue from a mouse model of phenylketonuria

Phenylketonuria (PKU), the most common inherited metabolic disorder, results from PAH mutations causing hyperphenylalaninemia and brain injury. While low-phenylalanine dietary therapy alleviates neurological symptoms, brain damage mechanisms remain unclear. Using our established PKU mouse model, we performed single-cell RNA sequencing of 38,678 brain cells to elucidate the cellular and molecular mechanisms underlying PKU-associated brain dysfunction. We identified widespread transcriptomic alterations across neuronal, glial, and immune compartments. Microglia and astrocytes exhibited elevated expression of oxidative stress and neuroinflammation genes, implicating neurotoxic roles. Neuronal populations displayed dysregulated synaptic transmission and plasticity genes, potentially contributing to cognitive impairments in PKU. Additionally, altered blood–brain barrier and cerebrovascular gene expression suggested vascular pathology contributes to brain injury. Our findings provide the first comprehensive cellular and molecular map of the PKU-affected brain, offering fresh insights into its complex pathophysiology and guiding development of specific therapeutics beyond dietary management.