UNTREATED NON-PHENYLKETONURICHYPERPHENYLALANINAEMIA - INTELLECTUAL AND NEUROLOGICAL OUTCOME

The intellectual, neurological, and neuropsychological outcome of pati ents with non-phenylketonuric-hyperphenyl alaninaemia (PKU-HPA) (serum phenylalanine levels under free diet < 600 mu mol/l) has not been sys tematically studied so far. We therefore tested 28 patients (mean age = 21.8, SD = 4.2 years) for IQ (WAIS-R/WISC-R), school performance, jo b career, clinical neurological examination, fine motor performance (m otor performance task), and selective and sustained attention (stroop task, Dot Pattern Exercise from the Sonneville visual attention task). In addition, cranial MRI (1.5 T unit) was obtained in 10 of these pat ients. Clinical-neurological examination revealed no significant abnor malities in the non-PKU-HPA patients. They also had a normal IQ (mean = 101.9, SD = 13.6). Compared to their healthy siblings, they attended a normal school and had a normal job career. The motor performance ta sk revealed no deficits in fine motor abilities. The patients pet-form ed normally in the stroop task and the dot pattern exercise. Their MRI s were normal. Our results indicate that patients with non-PKU-HPA are not at risk for developing intellectual, neurological, and neuropsych ological impairment, as described for patients with treated mild or cl assical phenylketonuria. From this point of view a dietary treatment i s not necessary in patients with hyperphenylalaninaemia.