Cognitive functions in patients with phenylketonuria in long-term treatment with tetrahydrobiopterin.

Cognitive functions were assessed in 9 patients with mild to moderate phenylketonuria (PKU) ranging from 6 to 18 years of age, who were in long-term treatment (>5 years) with 5-9 mg/kg/day tetrahydrobiopterin (BH4) on compassionate use, provided by Schircks Inc. An extensive study of cognitive functions (intelligence quotient (IQ), visuospatial, visual memory, fine motor, executive and attentional functions) was conducted, and behavior was assessed using the ADHD Rating Scale and the Behavior Rating Inventory of Executive Function (BRIEF). All patients had normal IQ (M=107, SD=10). The most notable area of impairment was fine motor function, but no significant difference was found between the PKU patients in BH4 treatment who participated in the current study and PKU patients in dietary treatment who participated in a previous study. These results, however, should be interpreted with caution. It is necessary to conduct further studies with a larger number of patients, using more sensitive tests of motor function and using the formulation of BH4 that is currently available.

[Clinical, biomedical , neurological and molecular study of 11 patients with new mutations in PAH gene]. / Estudio clínico, bioquímico, neurológico y molecular de 11 pacientes que presentan mutaciones nuevas en el gen PAH.

INTRODUCTION: PKU is an autosomal recessive disorder. There is a broad spectrum phenotype which depends mainly on residual enzymatic activity and also on other factors such as modifying genes and non-genetic factors. This fact makes us consider that a multidisciplinary study of these patients is necessary to improve knowledge of the condition. OBJECTIVE: To establish phenotype-genotype correlation and classify nine new mutations according to severity. PATIENTS AND METHODS: We evaluated the clinical data obtained from a multidisciplinary trial of 11 patients with PKU/HPA who presented with nine new mutations (P275S, P279fsdelC, V388delTG, N61/I62/T63fsdel5bp, P281S, P362T, H1OOR, I164V and Y168H) identified during a molecular study of the PAH gene done in Catalonia (Spain). RESULTS AND CONCLUSION: In our patients the genotype is correlated with the biochemical phenotype whereas the cognitive phenotype depends on determining factors such as early diagnosis and diet. Therefore, although PKU may be considered to be a complex characteristic, the mutations in the PAH gene are the main determining factor of the metabolic phenotype of PKU. A multidisciplinary study is the best way to understand and control these patients.