Neurological complications and behavioral problems in patients with phenylketonuria in a Follow-up Unit

ObjectiveTo investigate the relationship between neurological complications, neuroradiological findings, and behavioral problems, age at diagnosis and dietary control along the follow-up of the PKU patients in our metabolic unit.DesignRetrospective study of the PKU patients diagnosed and controlled in our unit from 1985 to 2010.MethodsRegistry of patients in a database with 50 items filled in by review of the clinical histories. Statistical study of the data (SPSS, 19.0 version).Results121 patients were included (median age: 16.0, range 1 month–46 years). 76% of them were diagnosed through neonatal screening. 12.4% had mild-PKU, 19% moderate-PKU and 68.6% classic-PKU. 88.4% of patients were treated with a protein-restricted diet, and 11.6% with BH4. 97.7% of the early diagnosed patients had normal IQ, while 46.3% of late diagnosed patients had mental retardation, 28.5% were borderline and 25% had normal IQ. In early diagnosed patients, there was a significantly negative correlation between IQ [mean (SD) 100 (11.1)] and the index of dietary control during the first six years of life [median (range) 310 (105–992)] and that of the immediately past year [348 (106–1127)] (p < 0.0001). The proportion of patients with late diagnosis and neurological and behavioral problems was significantly higher than that of the early diagnosed ones (p < 0.001). The proportion of early diagnosed patients with neurological and behavioral problems who had good, intermediate or poor dietary control during the first 6 years of life and the immediately past year was significantly different (p < 0.001).ConclusionsThe results show the impact of early diagnosis and good dietary treatment on the IQ and on the percentage of neurological complications and behavioral problems in PKU patients.