1. Kaufman S (1987) Tetrahydrobiopterin and hydroxylation systems in health and disease. In: Lovenberg W, Levine RA (eds) Unconjugated pteridines in neurobiology: basic and clinical aspects. Taylor and Francis, London, pp 1–28
2. Medical Research Council Working Party on Phenylketonuria (1993) Phenylketonuria due to phenylalanine hydroxylase deficiency: an unfolding story. Br Med J 306: 115–119
3. Pardridge WM (1998) Blood brain barrier carrier mediated transport and brain metabolism of amino acids. Neurochem Res 23:635–644
4. Bannon MJ, Bunney EB, Roth RH (1981) Mesocortical dopamine neurons: rapid transmitter turnover compared to other brain catecholamine systems. Brain Res 218: 376–382
5. Tillotson SL, Costello PM, Smith I (1995) No reduction in birth weight in phenylketonuria. Eur J Paediatr 154: 847–849