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Large neutral amino acids in the treatment of phenylketonuria (PKU)

  • Original Article
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Journal of Inherited Metabolic Disease

Summary

Large neutral amino acids (LNAAs) have been used on a limited number of patients with phenylketonuria (PKU) with the purpose of decreasing the influx of phenylalanine (Phe) to the brain. In earlier studies on mice with PKU (ENU2/ENU2), LNAAs were given and a surprising decline in blood Phe concentrations was observed. The formula used in the mouse experiment (PreKUnil) lacked lysine. Therefore, a new formulation of LNAAs (NeoPhe) was developed, introducing changes in the concentration of some amino acids and adding lysine, so that such a mixture could be used in humans. The new formula was found to be effective in reducing blood Phe concentration in mice by about 50% of the elevated levels. Patients with PKU were given LNAAs and blood Phe concentrations were determined in an open-label study. Three centres—in Russia, the Ukraine and the USA—took part in the study. NeoPhe was given at 0.5 g/kg per day in three divided doses to eight subjects with PKU and at 1.0 g/kg per day to three patients, for one week. The NeoPhe resulted in decrease of elevated blood Phe by 50% in both groups. The preliminary data from this study are encouraging and a double blind placebo-controlled trial will be required to show long-term efficacy and tolerance of LNAAs in the treatment of PKU.

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Abbreviations

CSF:

cerebrospinal fluid

5-HIAA:

5-hydroxyindolacetic acid

LNAA:

large neutral amino acid

Phe:

phenylalanine

PKU:

phenylketonuria

VIL:

valine, isoleucine and leucine

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Correspondence to R. Matalon.

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Communicating editor: Johannes Zschocke

Competing interests: None declared

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Matalon, R., Michals-Matalon, K., Bhatia, G. et al. Large neutral amino acids in the treatment of phenylketonuria (PKU). J Inherit Metab Dis 29, 732–738 (2006). https://doi.org/10.1007/s10545-006-0395-8

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  • DOI: https://doi.org/10.1007/s10545-006-0395-8

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