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pubmed:abstractText |
Two siblings with increased levels of serum phenylalanine were detected by newborn screening. The older sibling deteriorated neurologically and mentally, despite early dietary control, and died at the age of 6 1/2 years. In the younger sibling phenylalanine hydroxylase activity in liver tissue was normal. Further investigations revealed increased concentrations of biopterin derivatives in the blood, a low excretion of 5-hydroxyindole acetic acid in the urine, and a dihydropteridine reductase deficiency as the cause of hyperphenylalaninaemia. The parents of the siblings showed 50% of the normal dihydropteridine reductase activity in their fibroblasts grown in culture. Neurotransmitter therapy was started in the second child at the age of 6 months and this was followed by distinct neurological and mental improvement.
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