Osteopenia – a potential complication of phenylketonuria

Česká verzia

Authors: I. Žofková ¹; M. Bayer ²
Authors place of work: Endokrinologický ústav Praha Ředitelka: RNDr. Běla Bendlová, CSc. ¹; Dětská klinika LF a FN, Hradec Králové Přednosta: prof. MUDr. Milan Bayer, CSc. ²
Published in the journal: Prakt. Lék. 2011; 91(8): 482-484
Category: Of different specialties

Summary

Phenylketonuria is a consequence of altered phenylalanine degradation to 5-hydroxytryptofan, caused by mutations in the phenylalanine hydroxylase gene. Increased phenylalanine levels in blood and tissues are toxic to the brain and certain systems. Although the dominant feature of untreated phenylketonuria is progressive intellectual impairment, in a number of children and adolescents inadequate development of bone also occurs.

The fundamental pathogenic mechanism of bone damage is most probably due to the direct negative effect of phenylalanine on bone metabolism. Exclusion of phenylalanine from the diet protects the brain and, in some way, also the skeleton from phenylalanine’s toxic effects. On the other hand, in the absence of a supply of essential amino acids and osteoprotective molecules, bone development slows down. The possible osteotropic effect of a serotonin imbalance, induced by an interaction between the two different genes, is discussed.

Modern trends in treatment use tetrahydrobiopterin or phenylalanine-ammonia-lyase substitution, gene therapy and/or transplantation of liver cells.

Key words:
phenylketonuria, phenylalanine, 5-OH tryptophan, phenylalanine hydroxylase, PAH gen, tetrahydrobiopterin, serotonin.

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