PAH and phenylketonuria: Notably, one study recently received IND clearance from the US Food and Drug Administration (FDA) for the evaluation of AAV-mediated gene editing for the treatment of phenylketonuria (PKU), an inborn error of metabolism caused by mutations in the phenylalanine hydroxylase gene, resulting in an inability to metabolize phenylalanine (https://www.homologymedicines.com/news-story/homology-medicines-announces-worlds-first-gene-editing-clinical-trial-for-pku).