ABSTRACT

Phenylketonuria (PKU) is an autosomal recessively inherited disease.It occurs due to the mutations in the gene of phenylalanine hydroxylase (PAH).While the level of plasma phenylalanine (Phe) is within normal range after birth,the plasma Phe level of infants arise when they begin to feed.If appropriate medical and nutritional therapies are not implemented,many clinical sings,such as mental illness (IQ<50),skin-hair pigmentation disorders,growth retardation,microcephaly,epilepsy,behavioral disorders, hyperactivity, anxiety and so on may be observed.

There are several methods for treatment besides the most important one which is nutritional therapy. The first aim of nutritional therapy is to prevent the accumulation of phenylalanine in the blood and brain. The second purpose is to replace tyrosine deficiency due to lack of conversion of phenylalanine to tyrosine. When nutritional therapy is implemented, the growth and development of the child will return to normal, and complications may be prevented. The implementation of nutritional therapy is too easy at early ages. However, the compliance of diet is getting harder with aging. New treatment approaches can facilitate compliance with diet and clinical signs may be prevented. Some of the new therapeutic approaches are usage of large neutral amino acids, glycomacropeptide and tetrahydrobiopterin. Tetrahydrobiopterin treatment may be used only in patients with classical phenylketonuria who responds to treatment or metabolism disorders of BH4 metabolism.

Glycomacropeptide and large neutral amino acids can be used in nearly all patients.The use of phenylalanine ammonialyase which is in the study phase converts accumulated phenylalanine to its harmless metabolites.However, to ensure implementation of an effective nutritional therapy, it is necessary to provide strong communication between the family members and health professionals and the treatment methods must be widely described to family.Also supporting the nutritional therapy effectively with the new treatment approaches is important to prevent clinical signs and to improve the patient's life quality.