AAV-mediated gene transfer of WDR45 corrects neurologic deficits in the mouse model of beta-propeller protein-associated neurodegeneration
Beta-propeller protein-associated neurodegeneration (BPAN) is an ultra-rare, X-linked dominant, neurodegenerative disease caused by loss-of-function mutations in the WDR45 gene. It manifests in neurodevelopmental delay and seizures followed by secondary neurologic decline with dystonia/parkinsonism and dementia in adolescence and early adulthood and is characterized by progressive accumulation of iron in the basal ganglia. WDR45 encodes {beta}-propeller-shaped scaffold protein, or WIPI4, which plays an important role in autophagosome formation. While the mechanisms of how WIPI4 loss of function results in neurologic decline and brain pathology have not yet been established, findings of lower autophagic activity provide a direct link between impaired autophagy and neurologic disease in BPAN. Here we performed phenotypical characterization of a novel mouse model of BPAN, Wdr45_ex9+1g>a mouse. We identified hyperactive behavior and reduction of autophagy markers in brain tissue in Wdr45_ex9+1g>a hemizygous males as early as at 2 months of age. Given the early onset and spectrum of neurologic symptoms such as hyper-arousal and attention deficits in human patients, this model presents a disease-relevant phenotype and can be used in preclinical studies. We used this mouse model for a proof-of-concept study to evaluate whether AAV-mediated CNS-targeted gene transfer of WDR45 can provide therapeutic benefit and be considered a therapeutic paradigm for BPAN. We observed successful expression of human WDR45 transcripts and WIPI4 protein in the brain tissue, rescue of hyperactive behavior, and correction of autophagy markers in the brain tissue. This data demonstrates that WDR45 gene transfer can be a promising therapeutic strategy for BPAN.