This is a 10-year multi-center, prospective, longitudinal, single arm study evaluating immunologic, inflammatory and laboratory parameters associated with long-term Palynziq treatment in subjects with phenylketonuria (PKU) in the United States (US). Subjects in the US for whom a clinical decision has been made that they will receive pegvaliase to treat their PKU within 30 days following the date of enrollment in Study 165-501 (incident-users) or who have previously started treatment with pegvaliase at the date of enrollment in Study 165-501 (prevalent-users) are eligible for participation in Study 165-503.
Subjects enrolled at US sites participating in the 165-501 study.
Legal incapacity or limited legal capacity without legal guardian representation.
Subject is unable or unwilling to provide informed consent for the additional interventional burden of the study (blood sampling).