For decades, early dietary intervention in phenylketonuria was considered sufficient to normalize life outcomes. A growing body of evidence now challenges that assumption, suggesting that even well-managed adults with PKU face a constellation of aging-related changes that emerge earlier and more severely than in the general population — raising urgent questions about what "successful treatment" actually means across a lifetime.
This narrative review, published in the American Journal of Medical Genetics, synthesizes current evidence on accelerated aging in PKU adults. The analysis identifies oxidative stress — intrinsic to elevated phenylalanine metabolism — as the central driver, triggering downstream mitochondrial dysfunction, nuclear DNA damage, and epigenetic reprogramming. Cardiovascular aging features prominently, with PKU adults demonstrating measurable arterial stiffness and dyslipidemia. Metabolic complications including obesity, type 2 diabetes, and hypertension occur at elevated rates. Skeletal integrity is compromised through reduced bone mineral density, while neurological aging manifests as white matter lesions, measurable cognitive decline, and increased prevalence of mood disorders — all present despite continuous, guideline-adherent treatment.
This review is significant because it shifts the clinical framework for PKU from acute metabolic control to long-term aging phenotype management. Oxidative stress as an accelerating mechanism in PKU parallels what is now well-documented in other chronic metabolic conditions, such as type 2 diabetes and chronic kidney disease, lending biological plausibility to these findings. However, important caveats apply: PKU is a rare disorder with limited cohort sizes available for study, and most underlying mechanistic evidence derives from animal models or small observational human studies rather than longitudinal trials. The identification of potential aging biomarkers and treatment targets is nonetheless clinically meaningful, particularly as sapropterin and newer gene-therapy approaches extend survival in this population. This review rates as incrementally important — it reframes PKU as a premature aging condition, but confirmatory longitudinal human data remains the critical missing piece.
