Evaluation of PKU Sphere in Italy

Inclusion Criteria: * Patients diagnosed with PKU or hyperphenylalaninemia via new born screening and early treated, requiring \>50% of protein intake from protein substitute. * Aged 3 years and above. * Female patients of childbearing potential must have a negative urine pregnancy test prior to completing the screening procedures. * Willingly given, written, informed consent from the participant, 18 or more years, or from the parent/guardian for participants \< 18 years. * Willingly given, written assent (if appropriate) for those \< 18 years. Exclusion Criteria: * Pregnant, planning pregnancy or breastfeeding. * Intake of sapropterin dihydrochloride (Kuvan), PEG PAL or large neutral amino acids within 30 days prior to screening visit. * Patients currently taking their maximum recommended amount of protein substitute from a GMP based protein substitute. * Patients who are unable/unwilling to replace their current GMP protein substitute (if any) with PKU sphere. * Patients with known soya, milk or fish allergies / intolerance. * Individuals, who in the opinion of the investigator, are unable to comply with the requirements of the protocol. * Any co-morbidity, which in the opinion of the Investigator, would preclude participation in the study. * Patients who are currently participating in, plan to participate in, or have participated in an interventional investigational drug, food or medical device trial within 30 days prior to screening visit.