Systemic AAV-hGCDH Gene Therapy Alleviates Glutaric Acid Accumulation and Attenuates Chronic Brain Vacuolation in a Novel Mouse Model of Glutaric Aciduria Type I

Glutaric aciduria type 1 (GA1) is a rare neurometabolic disorder caused by glutaryl-CoA dehydrogenase (GCDH) deficiency, leading to the accumulation of neurotoxic metabolites that can cause both acute encephalopathic crises and progressive, insidious brain injury. Current management primarily relies on a protein-restricted diet, which remains therapeutically insufficient and burdensome for patients, highlighting the need for disease-modifying therapies. In this study, we established a novel GA1 mouse model using CRISPR/Cas9 technology and evaluated the preclinical efficacy of systemic recombinant adeno-associated virus (rAAV)-mediated gene therapy. Under standard dietary conditions without high-lysine challenge, our GA1 model exhibited sustained cerebral and hepatic glutaric acid (GA) accumulation and distinct chronic vacuolation in the hippocampus and cerebellum, mirroring the insidious-onset GA1 phenotype. Five-week-old mice received a single intravenous injection of rAAV-hGCDH using either rAAV2/8 or rAAV2/9 serotypes. Systemic rAAV-mediated gene therapy significantly reduced GA accumulation and attenuated chronic neuropathological changes in this GA1 mouse model for both serotypes. Our findings support the hypothesis that peripheral metabolic correction may play an important role in preventing the chronic neuropathological changes associated with GCDH deficiency. However, further investigation using tissue-specific expression systems is required to definitively delineate the relative contributions of hepatic versus central GCDH restoration to the observed neuroprotection.