Current recommendations are to maintain Phe levels < 360 µmol/L throughout life (US consensus) or < 600 µmol/L from the age of 12 (European consensus). Nevertheless, these recommendations do not take into account the individuality of each PKU patient who, in reality, reacts differently to Phe levels, with some patients with high levels (> 1200 µmol/L) escaping the neurological consequences of high Phe levels without this being well understood (OJRD 2018; 13: 149. Can untreated PKU patients escape from intellectual disability? A systematic review). It is therefore unclear what blood levels of phenylalanine are required during adolescence and adulthood to maintain an optimal cognitive, emotional and neurophysiological state in individual PKU patients, depending on their personal responsiveness to Phe.

Inclusion Criteria:

Patients :

• Age ≥ 18 years and < 59 years (age limit for ASEBA questionnaire)
• Person being monitored for PKU / HMP
• Relative living with the person
• Person who has received full information on the organization of the research and has not objected to the use of this data
• Compulsory membership of a social security scheme

Relatives:

• Age ≥ 18 years
• Person who has received full information on the organization of the research and has not objected to the use of this data
• Compulsory membership of a social security scheme

Exclusion Criteria:

• Refusal or linguistic, physical or psychological incapacity to to participate in the study
• Subjects under court protection
• Subjects under guardianship or curatorship

The study will be offered to all adult subjects and their close relatives who know the person well as part of the follow-up for PKU at the Centre de Référence des maladies héréditaires du métabolisme at the Nancy CHRU.

This study will be offered to a second metabolic reference center.