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PKU PKU is a disorder caused by Recessive alleles. The Disorder is found on the 12th chromosome PKU Pedigree How it is Inherited When a child is born with two copies ... – PowerPoint PPT presentation

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Title: Phenylketonuria

  • PKU is a disorder caused by Recessive alleles.
  • The Disorder is found on the 12th chromosome

PKU Pedigree
How it is Inherited
  • When a child is born with two copies of recessive
    alleles he inherits PKU
  • Boys and girls are equally at risk of inheriting
    this disorder.
  • Carriers are heterozygous for the trait
  • The disease affects at least one of every 16,000
    babies, mostly those of northern European
    background. Jews, Asians, and Africans are less
    commonly affected.
  • In this condition, an amino acid called
    phenylalanine builds up in the bloodstream,
    causing brain damage.
  • In order for a child to inherit PKU, both parents
    must be PKU carriers.

  • Nearly all cases of PKU in the United States are
    found in infant screenings
  • The Doctor or nurse draws a small sample of blood
    and then a Technician tests the blood to see if
    the trait is present on the 12th chromosome.

  • Mental Retardation
  • Behavioral and social problems
  • Seizures tremors or jerking movements
  • Rocking
  • Hyperactivity
  • Stunted Growth
  • Skin Rashes
  • Small head size
  • Vomiting
  • A musty odor in the skin, breath or urine caused
    by too much Phenylketonuria

The inability to change Phenylalanine Hydroxylase
to Phenylalanine causes all of these symptoms.
  • A long life diet of a reduced protein diet is
    recommended to reduce build up of phenylalanine,
    but it can never be fully treated
  • Kuvan is the first FDA approved drug for treating

Life Expectancy
  • Although PKU is a life-long disease, people who
    have PKU have the same average life expectancy as
    those who do not have the disease.

Genetic counseling
  • Genetic counselors have limited advice they can
    offer to people with PKU.
  • Most genetic suggest a low or no protein diet
    depending on how sever the disease is.
  • They may also suggest a special formula that
    delivers the amino acids the body is deprived of
    due to PKU.

  • - How common is it that you deal with this
    disease?  PKU is not that uncommon as far as
    genetic diseases go.  I dont know the exact
    incidence but you can look that up.  Most of the
    kids with PKU in houston are seen at our
    metabolic genetics clinic at TCH.
  • -They are usually seen by the metabolic
    geneticist (MD), a metabolic nurse and a
    dietician. These specialists help coordinate
    their care and special dietary concerns and
  • -The diagnosis is almost always made on the
    newborn screening test.
  • Sometimes the newborn screen is falsely abnormal
    which is why it is repeated and then a
    phenylalanine level is obtained.  If PKU is
    confirmed the baby is immediately started on the
    special diet.
  • -Is this disease preventable by taking special
    precautions? The disease itself is not exactly
    preventable unless you do prenatal testing in a
    couple at risk.  However it is the bad effects of
    the disease that are completely preventable. 
  • - Without the special diet and formula, people
    with PKU will have mental retardation.  If they
    stick with the diet, their intelligence is in
    normal range.

  • 3. How must people living with phenylketonuria mod
    ify parts of their lifestyle? The biggest
    lifestyle adjustment is diet.  It depends on
    their phe level, but most classic PKU kids can
    have NO protein!
  • Think about it, no cheese, no meat, no soda (look
    on the can). The diet is very restrictive and
    difficult to stick to as you can imagine. 
  • To supplement, people with PKU also have to drink
    a special formula so they can get essential amino
    acids that they dont get in their diet.  I have
    never tasted this personally but I have heard
    that it is nasty!
  •   You would think we could get it to taste good
    but no luck.  There are special companies that
    make foods like pasta and such for people with
    PKU also.  Frequent blood draws are also
    necessary to check Phe levels.
  • -What problems, if any, do people with
    phenylketonuria face later in life? Good
    question!  In the old days (10 years or so ago)
    we used to think that people with PKU could stop
    the diet when they reached adulthood (brain stops
    growing etc) however, many adults expressed
    difficulites when off diet.
  • -They say they cant focus and have trouble with
    tasks and actually lose IQ points. So it seems
    the diet is important long term.  This is
    especially important for women. 
  • -If a woman has PKU and becomes pregnant (off
    diet) her baby is at a very high risk to have
    mental retardation and other problems like very
    small head size. 
  • -The baby does not have PKU but it is the effect
    of the high levels of phenylalanine in the mom's
    system that cross the placenta and hurt the
    baby.  So women with PKU should stay on the diet
    their whole lives and be especially vigilant when
    planning a pregnancy.
  • - Any other interesting facts about
    phenylketonuria?Other interesting facts  There
    is a new treatment being tried out for PKU (sorry
    dont remember the name). 
  • - Also for kids in Texas with PKU we hold a camp
    every summer called camp Phever.  It is held at
    Camp For All and is a collaboration between the
    genetics groups at Baylor/TCH and UT/Hermann. The
    kids love it.

Works CitedBatshaw, Mark L. "The Potential for
Gene Therapy in Inborn Errors of Metabolism A
Case Example" 1999. National PKU
News. 25 Jan. 2009 lthttp//
rch/genether.htmgt. Calvin College Hekman Library
openURL resolver.Carter, Stien J. "Amino Acids
and Proteins" 1996. 25 Jan.
2009 lthttp//
tein.htmgt. Furman, Patti. "Fw Stratford Biology
Project (Interview)." E-mail to the author. 22
Jan. 2009. Hull, Janet S. "Phenylketonuria (PKU)
- Aspartame" 2002. Asparatame
Detox Program. 25 Jan. 2009 lthttp//www.sweetpoi"Phenylketonuria
(PKU)" 2007. Mayo Clinic. 25 Jan.
2009 lthttp//
2006. 25 Jan. 2009 lthttp//
.php?id16gt. "The Inborn Error of Metabolism in
PKU." 2007. BioMarin Pharmaceutical Inc.
25 Jan. 2009 lthttp//
ceOfPKU.aspxgt. "What is PKU?."
Children's PKU Network. 25 Jan. 2009
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