A Long Term, Post-marketing Study of Immune Response in Patients Receiving Palynziq Treatment for PKU (PALisade)

Must be enrolled in the 165-501 PALace study. Subjects currently receiving or who plan to receive pegvaliase treatment within 30 days after the date of enrollment in the 165-501 study, including subjects who previously received pegvaliase as part of the clinical development program and have completed study participation