Rescue of glutaric aciduria type I in mice by liver-directed therapies
Mercedes Barzi, Collin G. Johnson, Tong Chen, Ramona M. Rodriguiz, Madeline G. Hemmingsen, Trevor Gonzalez, Alan Rosales, James Beasley, Cheryl K. Peck, Yunhan Ma, Ashlee R. Stiles, Timothy C. Wood, Raquel Maeso‐Díaz, Anna Mae Diehl, Sarah P. Young, Jeffrey I. Everitt, William C. Wetsel, William R. Lagor, Beatrice Bissig-Choisat, Aravind Asokan, Areeg El‐Gharbawy, Karl‐Dimiter Bissig
Abstract
Glutaric aciduria type I (GA-1) is an inborn error of metabolism with a severe neurological phenotype caused by the deficiency of glutaryl–coenzyme A dehydrogenase (GCDH), the last enzyme of lysine catabolism. Current literature suggests that toxic catabolites in the brain are produced locally and do not cross the blood-brain barrier. In a series of experiments using knockout mice of the lysine catabolic pathway and liver cell transplantation, we uncovered that toxic GA-1 catabolites in the brain originated from the liver. Moreover, the characteristic brain and lethal phenotype of the GA-1 mouse model was rescued by two different liver-directed gene therapy approaches: Using an adeno-associated virus, we replaced the defective Gcdh gene or we prevented flux through the lysine degradation pathway by CRISPR deletion of the aminoadipate-semialdehyde synthase ( Aass ) gene. Our findings question the current pathophysiological understanding of GA-1 and reveal a targeted therapy for this devastating disorder.