Pilot study to evaluate the effects of tetrahydrobiopterin on adult individuals with phenylketonuria with measurable maladaptive behaviors.

[phenylketonuria]

To evaluate the effects of tetrahydrobiopterin (BH 4 ) on maladaptive behavior in patients with phenylketonuria (PKU ).In an effort to determine if BH 4 has any effects on the central nervous system , we studied 10 individuals with PKU and measurable maladaptive behaviors for 1 year . Behavioral assessments using the Vineland Adaptive Behavior Scales -Second Edition and a PKU Behavior Checklist were obtained at baseline , 6 months , and at the end of the study . Biochemical measures including plasma amino acids were obtained quarterly , and phenylalanine (Phe ) and tyrosine (Tyr ) were obtained monthly .Out of the 10 subjects , 2 were responders to BH 4 , as determined by a blood Phe reduction >30 %. While blood Phe in the 8 nonresponders did not change significantly throughout the study , their Tyr levels were significantly higher at 6 months (p =0 .012 ), but not at 12 months (p =0 .23 ). By the end of the study , 8 subjects exhibited fewer maladaptive behaviors on the components of the Vineland Maladaptive Behavior Index , and all 10 had lower total scores on the PKU Behavior Checklist .These findings suggest that there may be direct effects of BH 4 on the central nervous system , independent of lowering blood Phe .

Diseases
Validation

Diseases presenting "behavioral assessments" symptom

locked-in syndrome

phenylketonuria

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