In conclusion, in early treated PKU patients: a) white matter alterations emerge during late childhood and increase from the second decade
of life onwards; b) the severity of white matter alterations is independently and cumulatively influenced by patient’s age and level of phenylalanine
between subsequent MRI examinations; c) serial MRI examinations
disclosed a remarkable interindividual variability in white matter alterations outcome, which remains unexplained by the disease-associated
biochemical variables; d) intellectual and MRI white matter outcome
probably follow different independent trajectories.