Volumetric brain reductions in adult patients with phenylketonuria and their relationship with blood phenylalanine levels.

Background: Continued dietary treatment since early diagnosis through newborn screening programs usually prevents brain-related complications in phenylketonuria (PKU). However, subtle neurocognitive and brain alterations may be observed in some adult patients despite early treatment. Nevertheless, neuropsychological and neuroimaging studies in the field remain scarce.