Phenylketonuria(pku)

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Phenylketonuria(pku)

  1. 1. PHENYLKETONURIA (PKU)
  2. 2. <ul><li>The normal metabolism of phenylalanine </li></ul><ul><li>(pathways a and b ) </li></ul>PHENYLALANINE HYDROXYLASE PHENYLALANINE Dietry sources, particularly plant proteins BODY PROTEINS BREAKDOWN TYROSINE © 2008 Paul Billiet ODWS (b) (a)
  3. 3. <ul><li>The abnormal metabolism in phenylketonuric subjects </li></ul><ul><li>(pathway c ) </li></ul>HYDROXYPHENYLACETIC ACID PHENYLACETIC ACID * *Agents, thought to be responsible for mental retardation © 2008 Paul Billiet ODWS (c) (c) PHENYLALANINE* Dietry sources, particularly plant proteins BODY PROTEINS (b) (a) PHENYLALANINE HYDROXYLASE
  4. 4. Test <ul><li>Ferric chloride + urine of new born baby  Green colour in the presence of ketone bodies </li></ul>© 2008 Paul Billiet ODWS
  5. 5. Treatment <ul><li>A strictly controlled phenylalanine free diet </li></ul><ul><li>up to the age of about 14 years old </li></ul><ul><li>phenylalanine is itself an essential amino acid small doses must be supplied </li></ul><ul><li>After this age the growth and development of the brain is not affected by high levels of phenylalanine in the body </li></ul>© 2008 Paul Billiet ODWS
  6. 6. Frequency <ul><li>1 in 10 000 in Caucasians of NW Europe </li></ul>© 2008 Paul Billiet ODWS
  7. 7. Causes <ul><li>A single mutant recessive allele of the Phenylalanine Hydroxylase (PAH) gene Locus : Long arm of Chromosome 12 </li></ul><ul><li>Dietary excess of plant proteins which results in the exhaustion of a protein cofactor (pterin) needed by the enzyme </li></ul>© 2008 Paul Billiet ODWS
  8. 8. Evolution <ul><li>Heterozygotes (carriers) are thought to be less susceptible to toxins produced by the moulds Aspergillus and Penecillium </li></ul><ul><li>These grow on foods in damp wet climates (e.g. NW Europe) </li></ul><ul><li>Heterozygous women show lower spontaneous abortion rates </li></ul>© 2008 Paul Billiet ODWS

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