Phenylketonuria (PKU) is a genetic condition where the body can't properly break down an amino acid called phenylalanine (Phe). If Phe builds up, it can cause brain problems. PKU patients often follow a strict diet, but a new medicine called *Palynziq* might help. Palynziq is a treatment approved by the FDA (Food and Drug Administration) that can lower Phe levels, allowing people with PKU to have a more flexible diet.

This study observes how Palynziq affects diet, brain health, and overall well-being over three years. Only adults aged 16 and older with a PKU diagnosis and a Palynziq prescription can join. Participants must be able to provide consent and have no other major health issues. If successful, participants could continue for up to five years.

• Study Duration: 3 years, with an optional 2 more years
• Eligibility: Must be 16 or older with a PKU diagnosis
• Involves regular monitoring of health and diet