1 From the Departments of Pediatrics, Clinical Genetics, Nutritional Sciences, Waisman Center on Mental Retardation and Human Development, University of Wisconsin, Madison; Laboratory of Neurochemistry, National Institutes of Health, Bethesda, Maryland; Departments of Pediatrics and Genetics, University of Illinois, Chicago; Department of Pediatrics, State University of New York at Buffalo, Buffalo; and Department of Biochemistry and Molecular Biology and Analytical Chemistry Center, University of Texas Medical School at Houston, Houston
Hyperphenylalaninemia due to a biopterin synthesis defect was detected in an infant with decreased biopterin and increased neopterin levels in plasma and urine. Tetrahydrobiopterin (BH4) administration normalized plasma phenylalanine levels. CSF biopterin and neurotransmitter metabolite levels were normal and with the infant's normal growth and development suggest that the defect in biopterin synthesis did not affect CNS biopterin metabolism. Comparison of plasma and urine pterin levels from this patient with levels reported in patients who have neurologic complications fails to reveal differences that would distinguish patients at risk for neurologic problems. CSF pterin and neurotransmitter levels may correlate with neurologic function in these patients. CSF pterin and neurotransmitter determinations should be performed prior to initiation of neurotransmitter precursor and BH4 replacement therapies in patients who were determined to have biopterin synthesis defect(s).
Key Words: hyperphenylalaninemia phenylketonuria neurotransmitters tetrahydrobiopterin screening
Submitted on March 8, 1984