Efficiency of long-term tetrahydrobiopterin monotherapy in phenylketonuria

Abstract

Phenylketonuria, an inborn error of phenylalanine metabolism, occurs with a frequency of about 1 in 10 000 births and is treated with a strict dietary regimen. Recently, some patients with PKU have been found to show increased tolerance towards phenylalanine intake while receiving tetrahydrobiopterin (BH4) supplementation. We have treated two infants with BH4-responsive PKU with BH4 for more than 2 years. No additional dietary control was required to maintain blood phenylalanine concentrations in the desired range. Both children have shown normal development. Generally, our results suggest that BH4 treatment might be an option for some patients with mild PKU, as it frees them from dietary restrictions and thus improves their quality of life. © SSIEM and Kluwer Academic Publishers.