HIGHER BIOLOGY PKU ESSAY

The effect of PAH mutations on hepatic enzyme function and the resultant disruption to Phe homeostasis has been well described, but the major clinical effect in PKU relates to brain development and cognitive function. Metabolic studies in phenylketonuria. Conversion of Phe to Tyr is via a pathway involving the para-hydroxylation of the benzene by PAH, the cofactor BH 4 and molecular oxygen. Department of Health, Government of Western Australia; Animal models have been used to demonstrate inhibition of sterol synthesis by various phenolic compounds.

The role of reversible phosphorylation in the hormonal control of phenylalanine hydroxylase in isolated rat proximal kidney tubules. Decreased coenzyme Q 10 ubiquinone; CoQ 10 concentrations have been found in both plasma and in lymphocytes from patients with PKU. Australian Society for Inborn Errors of Metabolism. In older children, protein intake is calculated each day, whereby a child is allocated a certain number of grams or units of daily protein, depending upon longitudinal plasma Phe concentrations. The contents of articles or advertisements in The Clinical Biochemist — Reviews are not to be construed as official statements, evaluations or endorsements by the AACB, its official bodies or its agents.

higher biology pku essay

A low Phe diet is used for treatment with, initially, the small amounts of Phe coming hiigher breast milk or commercial infant formula considered sufficient intake in babies. Journal List Clin Biochem Rev v. Adapted from Huften IG et al Department of Health, Government of Western Australia; Our understanding has changed dramatically in the 70 years that have elapsed since the discovery of PKU. The mutations can be of various types: Foods such as eggs, milk, cheese, meat, poultry, fish, dried beans and legumes which are high in protein are excluded from the diet.

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PKU patients under dietary treatment can have low concentrations of trace elements and cholesterol, and some disturbance to folate metabolism as well as distortion of their fatty acid profile. Abstract Phenylketonuria PKU higner an autosomal recessive inborn error of phenylalanine Phe metabolism resulting from deficiency of phenylalanine hydroxylase PAH.

As with many other metabolites, Phe concentrations are regulated to a steady state level with dynamic input and bioolgy flux. As discussed above, conventional PKU diagnosis is based on the aberrant metabolic bioloyg, disease causing mutations and associated polymorphic haplotypes can be analysed at the PAH locus.

higher biology pku essay

Although dietary restriction of Phe is the cornerstone of treatment for PKU, the practicalities of following biologgy strict diet have led to trials of additional therapies. Phenylalanine Hydroxylase PAH catalyses the stereospecific hydroxylation of l -Phe, the committed step in the degradation of this amino acid. Other trials involving the use of recombinant retroviral vectors have been abandoned following the observation that these vectors may induce leukaemia-like disorders.

higher biology pku essay

While the para -hydroxylation of Phe is essential for the rupture of the benzene ring, it is not required for further metabolism of the alanine side chain. Regional mapping of the phenylalanine hydroxylase gene and the phenylketonuria locus in the human genome.

Phenylketonuria: An Inborn Error of Phenylalanine Metabolism

Australian Society for Inborn Errors of Metabolism. This hypothesis has led to LNAA supplementation trials. Disorders of tetrahydrobiopterin and related biogenic amines. Adapted from Scriver and Kaufman In milder forms of PKU non-PKU HPAwhere there is residual enzyme activity, blood Phe concentrations may be only mildly elevated even under conditions of poor treatment diet compliance.

Moreover, decreased or absent PAH pu can lead to a deficiency of Tyr and its downstream products, including melanin, l -thyroxine and the cate-cholamine neurotransmitters.

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Phenylketonuria: An Inborn Error of Phenylalanine Metabolism

ISSN — Hoppe-Seylers Z Physiol Chem. Serum lipid concentrations in subjects with phenylketonuria and their families. Incidence of PKU by population.

Author information Copyright and License information Disclaimer. Am J Clin Nutr. Large neutral amino acids block phenylalanine transport into brain tissue in patients with phenylketonuria. The human PAH gene Figure 5 is located on chromosome 12q Its discovery over 70 years ago and scientific investigation has established the link between metabolic disease and intellectual impairment, led to the development of neonatal screening programs across the globe, and demonstrated how effective treatment can lead to a near normal outcome for affected individuals.

Association with dietary status. Pathogenesis of Intellectual Impairment in PKU The effect of PAH mutations on hepatic enzyme function and the resultant disruption to Phe homeostasis has been well described, but the major clinical effect in PKU relates to brain development and cognitive function.

Phe exists as d and l enantiomers, and l -Phe is an essential amino acid required for protein synthesis in humans. The discovery of phenylketonuria. The contents of articles or advertisements in The Clinical Biochemist — Reviews are not to be construed as official statements, evaluations or endorsements by the AACB, its official bodies or its agents.