Generation and characterization of phenylketonuria mouse models carrying East Asian–relevant patient-derived PAH mutations

Abstract

Phenylketonuria (PKU) is an inherited metabolic disorder caused by mutations in the Pah gene, resulting in impaired phenylalanine hydroxylase activity and elevated blood phenylalanine levels. Although dietary management and enzyme replacement can reduce disease burden, they require lifelong treatment and do not correct the underlying genetic defect. Here, we generated two PKU mouse strains carrying patient-derived PAH mutations, p.R111X and p.R413P, which are relatively frequent in East Asian populations and particularly relevant to Japanese PKU patients. Homozygous mice for each mutation exhibited marked hyperphenylalaninemia and coat hypopigmentation, recapitulating key features of classical PKU. The Pah R111X strain showed a more severe biochemical and pigmentation phenotype than the Pah R413P strain, suggesting mutation-dependent differences in allele severity, likely reflecting the null nature of p.R111X and possible residual function of p.R413P. We further established compound heterozygous Pah R111X/R413P mice and performed a preliminary evaluation of genome editing-based correction using allelic exchange or interhomolog recombination. RT-PCR analysis of liver tissue detected partial restoration of wild-type Pah transcripts, supporting the utility of these patient-mutation-based PKU mice as a platform for evaluating endogenous gene correction strategies.