Phenylketonuria (PKU)Phenylketonuria (PKU)

PKU at a GlancePKU at a Glance

Name of disorder: Name of disorder: Phenylketonuria (PKU)Phenylketonuria (PKU)

OMIM number: 261600OMIM number: 261600 inheritance pattern: autosomal inheritance pattern: autosomal

recessiverecessive

PKU At A GlancePKU At A Glance

PKU is a metabolic disorder PKU is a metabolic disorder caused by a deficiency of the caused by a deficiency of the liver enzyme phenylalanine liver enzyme phenylalanine hydroxylase. It prevents normal hydroxylase. It prevents normal metabolization ofmetabolization of

PKU At A GlancePKU At A Glance

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

PKU At A GlancePKU At A Glance

Untreated individuals may give Untreated individuals may give off a musty odor and they off a musty odor and they excrete large amounts of excrete large amounts of phenylalanine in their urine.phenylalanine in their urine.

Phe to Tyr ConversionPhe to Tyr Conversion

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

Phe to Tyr ConversionPhe to Tyr Conversion

phenylalanine hydroxylase, phenylalanine hydroxylase, which converts phenylalanine to which converts phenylalanine to tyrosine. tyrosine.

Phe to Tyr ConversionPhe to Tyr Conversion

Metabolic PathwaysMetabolic Pathways

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

Metabolic PathwaysMetabolic Pathways

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

PKU GeneticsPKU Genetics

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

PKU GeneticsPKU Genetics

PKU OnsetPKU Onset

The inability to metabolize PKU The inability to metabolize PKU exists from the time the infant is exists from the time the infant is in the womb. in the womb.

Infants are screened for PKU by Infants are screened for PKU by a blood test shortly after birth. a blood test shortly after birth.

PKU OnsetPKU Onset

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

PKU OnsetPKU Onset

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

PKU TreatmentPKU Treatment

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

PKU TreatmentPKU Treatment

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

PKU TreatmentPKU Treatment

Artificial protein substitutes are Artificial protein substitutes are given which contain amino given which contain amino acids without phenylalanineacids without phenylalanine

PKU PrognosisPKU Prognosis

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

PKU PrognosisPKU Prognosis

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

PKU PrognosisPKU Prognosis

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