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Phenylketonuria (PKU)

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Presentation on theme: "Phenylketonuria (PKU)"— Presentation transcript:

1 Phenylketonuria (PKU)

2 PKU at a Glance Name of disorder: Phenylketonuria (PKU)
OMIM number: inheritance pattern: autosomal recessive

3 PKU At A Glance PKU is a metabolic disorder caused by a deficiency of the liver enzyme phenylalanine hydroxylase. It prevents normal metabolization of

4 PKU At A Glance phenylalanine (Phe), one of the essential amino acids that cannot be manufactured by the body and must therefore be consumed in protein rich foods.

5 PKU At A Glance Untreated individuals may give off a musty odor and they excrete large amounts of phenylalanine in their urine.

6 Phe to Tyr Conversion Enzymes are structures that allow amino acids to combine by acting on a substrate and producing a new product. Individuals with PKU have a deficiency in the enzyme

7 Phe to Tyr Conversion phenylalanine hydroxylase, which converts phenylalanine to tyrosine.

8 Phe to Tyr Conversion

9 Metabolic Pathways In individuals with PKU, phenylalanine can’t be converted into tyrosine, and the metabolic process stops short of producing the needed end products.

10 Metabolic Pathways Phenylalanine builds up in the body to toxic levels, causing mental retardation.

11 PKU Genetics The PKU gene is found on the q arm of chromosome 12, locus 24.1 in the phenylalanine hydroxylase gene

12 PKU Genetics

13 PKU Onset The inability to metabolize PKU exists from the time the infant is in the womb. Infants are screened for PKU by a blood test shortly after birth.

14 PKU Onset High levels of phenylalanine in the blood indicate an inability to process the amino acid, and thus indicate that an individual is affected by the disorder.

15 PKU Onset Testing must be accomplished quickly since the inability to process phenylalanine means it can build up to toxic levels and cause severe mental retardation.

16 PKU Treatment The only treatment available for PKU is a diet where phenylalanine levels are strictly limited.

17 PKU Treatment Meat, fish, eggs, cheese, milk products, legumes, and bread are all foods that have high levels of phenylalanine

18 PKU Treatment Artificial protein substitutes are given which contain amino acids without phenylalanine

19 PKU Prognosis If the condition was not diagnosed early and a special diet started, the indidivudal will suffer severe and irreversable brain damage.

20 PKU Prognosis If detected early, the individual will develop normally but will have to follow the special diet at least until adolescence, if not throughout their entire life.

21 PKU Prognosis Women with PKU who wish to become pregnant must also eat the special diet, since children in the womb affected with PKU will not be able to metabolize the phenylalanine the mother ingests.

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