The National Center for Advancing Translational Sciences (NCATS), through its Therapeutics for Rare and Neglected Diseases (TRND) program, is collaborating with the National Human Genome Research Institute (NHGRI) to advance an AAV9 Propionyl-CoA Carboxylase (PCCA) gene therapy candidate as a possible treatment for Propionic Acidemia (PA). The overall objective of this task order is for the contractor to evaluate the efficacy and safety of an Adeno-associated virus 9 (AAV9) Propionyl-CoA Carboxylase (PCCA) gene therapy candidate in propionic acidemia (PA) disease mouse models, previously developed at NHGRI, and develop bioanalytical assay methods that will be used to measure biodistribution and enzyme activity resulting from PCCA transgene expression.