Published studies

Transport of amino acids (including tyrosine and phenylalanine) from blood to brain


Published: September 2017 in Plos One
Article: Transport of amino acids (including tyrosine and phenylalanine) from blood to brain
Authors: WG van Ginkel, D van Vliet, JGM Burgerhof, P de Blaauw, ME Rubio-Gozalbo, MR Heiner-Fokkema, FJ van Spronsen
Contact: Wiggert van Ginkel
Link to article:

It is currently unknown why the IQ of Tyrosinemia type 1 patients is lower when compared to healthy control participants. Some theories exist. It has been hypothesized that increased tyrosine concentrations and/or decreased phenylalanine concentrations could lead to changes in brain function.

Tyrosine and phenylalanine are both necessary for the growth of large parts of the body. Muscles for example require tyrosine and phenylalanine for growth. Tyrosine and phenylalanine are rimportant for brain functioning as well. To get inside your brain, tyrosine and phenylalanine need to pass through the blood-brain barrier. It is possible that high blood concentrations of tyrosine could lead to high tyrosine concentrations in the brain as well. On the other hand, low blood phenylalanine concentrations could in turn lead to low brain phenylalanine concentrations. In this research project, we aimed to investigate if this is indeed the case. This was done using various theoretical models that were worked out by other researchers some years ago.

The results of this study showed that high blood tyrosine concentrations lead to high brain tyrosine concentrations. On the other hand, only a small decrease in blood phenylalanine concentrations can lead to brain phenylalanine concentrations that are much lower than expected. Both, the high tyrosine and low phenylalanine concentrations could have a negative effect on the brain. Although only theortical, it is felt that levels that are too high or too low need to be prevented.


It's hard to believe, but there are no
european guidelines for Tyrosinemia type 1 yet!


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