ALL ABOUT PKU
-Rare inherited disorder
- Mutations in the PAH gene cause phenylketonuria.
-Enzyme: Phenylalanine hydrase.
-Found in the liver
-Located on long arm of chromosome number 12 between positions 22 and 24
Thanks a Lot, Mom and Dad....
-Autosomal recessive mutation
-Must receive two mutated genes from both parties
-Won't develop if only one gene is passed, but child will become a carrier
-Responsible for processing phenylalanine (building block of proteins)
-Change single amino acids. Most common: Arginine into triptophan at position 408.
-Also delete small amounts of DNA, causing gene disruptions.
-Makes tyrosine, which makes several hormones, melanin, and neurotransmitters.
-Large levels of phenylalanine can be very harmful to the brain, causing mental delay.
How Does PKU Work?
Usually occurs when the enzyme phenylalanine hydroxylase is absent or severely
Phenalalanine, an essential amino acid, cannot be broken down (and cannot be converted
Accumulates in large quantities throughout the body
Symptoms of PKU
Children with PKU appear normal at birth but develop mental retardation if not treated
Tend to have lighter coloured skin, hair and eyes (unable to be converted into tyrosine,
which is involved with producing the melanin (pigment)
Likely to have eczema and seizures
Variety of neurological symptoms
Musty-smelling sweat and urine (due to the byproduct phenylacetic acid)
Treatment for PKU
Infants with PKU must be treated early; Symptoms irreversible if not treated early
Untreated newborns develop between the ages three months and five months
Screening phenylalanine levels in newborns to detect PKU before symptoms start to
develop (Analyze blood for phenylalanine concentration taken by pricking the heel of the
Newborns should have a special low phenylalanine diet
Diet avoids many natural foods, including breast milk (contain higher levels of
phenylalanine than PKU patients can tolerate)
Diet may include low protein, natural foods, including fruits, vegetables, and some
Ensure that normal levels are maintained by monitoring blood phenylalanine levels
This diet must be used throughout the person’s life
- Basic Research of Phenylketonuria (PKU). 2015. University of Southern California.
- Güttler, Flemming, and Guldberg, Per(Aug 2011) Phenylketonuria. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0006027.pub2]
- Learning About Phenylketonuria. (n.d.). Retrieved May 19, 2015, from https://www.genome.gov/25020037
- National Institutes of Health Consensus Development Conference Statement:Phenylketonuria: Screening and Management.
- Phenylketonuria. (2014). In K. L. Lerner & B. W. Lerner (Eds.), The Gale Encyclopedia of Science (5th ed.). Farmington Hills, MI: Gale.