Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. A birth defect that causes an amino acid called phenylalanine to build up in the body. Newborns should be screened for PKU. Untreated phenylketonuria can lead to brain damage, intellectual disabilities, behavioural symptoms or seizures. Treatment includes a strict diet with limited protein.

1. PHENYLKETONURIA
Dr. V. MAGENDIRA MANI., M.Sc., M.Phil., Ph.D.,TNSET
Assistant Professor of Biochemistry
Islamiah College (Autonomous), Vaniyambadi
magivbio@gmail.com; 9486000227

2. Phenylketonuria
● Phenylketonuria (PKU) is an inborn error of metabolism
that results in decreased metabolism of the amino acid
phenylalanine
● It is due to the defetct of enzyme phenylalanine
hydroxylase that breaks down phenylalanine.
● This enzyme normally converts phenylalanine to another
amino acid tyrosine

3. When PAH activity is reduced, phenylalanine accumulates and
is converted into phenylpyruvate (phenylketone), which can
be detected in the urine.

4. ● PKU is caused by a mutated gene for PAH enzyme due to
defect in the biosynthesis of cofactor tetrahydrobioptrin
(BH4).
● The PAH gene is located on chromosome 12 .
● PAH deficiency causes a wide spectrum of disorders
including PKU and hyperphenylalaninemia

5. Phenaylalanine
● It is essential amino acid
● Normally degraded by way of the tyrosine pathway
● Phenylalanine and tyrosine are precursor amino acids for
important compounds Like: Thyroid hormone,
Neurotransmitters, Melanin etc.,

6. Hyperphenylalaninemia'
strictly means elevated
blood phenylalanine, it is
usually used to describe
a group of disorders
other than classic PKU.

7. ● Normal blood phenylalanine level is about 1 mg/dl.
● In classic PKU, levels may range from 6 to 80 mg/dl,
● Classic PKU and the other causes of
hyperphenylalaninemia affect about 1 of every 10,000 to
20,000

8. PKU is inherited in families in an autosomal recessive
pattern. Autosomal recessive inheritance means that a
person has two copies of the gene that is altered. Usually,
each parent of an individual who has PKU carries one copy
of the altered gene. Since each parent also has a normal
gene, they do not show signs or symptoms of PKU.

13. If it isn't treated, damage to
the brain and
nervous system can lead to:
1. learning disabilities
2. behavioural difficulties
3. epilepsy

14. Infants with PKU appear normal at birth. Many have blue eyes and fairer Hair
and skin than other family members.
About 50% of untreated infants have early symptoms, such as
❖ vomiting,
❖ irritability
❖ eczema-like rash,
❖ and a musty odor to the urine and the body.
❖ Later, severe brain problems occur, such as mental retardation and
seizures
❖ Jerking movements in arms and legs, Tremors, Mood disorders,
Microcephaly,

15. Other commonly noted features in untreated children
include:
Microcephaly (small head),
Prominent cheek and upper jaw bones
with widely spaced teeth

16. Microcephaly
Microcephaly is a condition
where the head
(circumference) is smaller
than normal

17. Poor development of
tooth enamel,
and decreased body
growth.

18. Pregnancy and PKU
Women who have PKU and become pregnant are at risk of another form of the
condition called maternal PKU. If women don't follow the special PKU diet
before and during pregnancy, blood phenylalanine levels can become high and
harm the developing fetus or cause a miscarriage.
Complications at birth may include:
● Low birth weight
● Delayed development
● Facial abnormalities
● Abnormally small head
● Heart defects and other heart problems
● Intellectual disability
● Behavioral problems

19. Follow a low-phenylalanine diet
Women with PKU can prevent birth defects by sticking to or
returning to a low-phenylalanine diet before becoming pregnant.
Consider genetic counseling.
If you have PKU, a close relative with PKU or a child with PKU,
you may also benefit from genetic counseling before becoming
pregnant.
Prevention

20. Diagnosis

22. Treatment
Oral administration of tetrahydrobioptrin ( a cofactor in the oxidation
of phenylalanine) is a good potential for PKU sufferers .
Foods to avoid - High protein foods, such as:
Meat, Fish, Poultry, Eggs, Cheese
Milk and products, Dried beans, and peas

23. They usually also need to consume a special formula
known as Lofenalac

24. ● No cure
● Permanent monitoring of blood phenylalanine levels
● A strictly controlled phenylalanine free diet up to the age of about 14
years old.
● Phenylketonuria (PKU) can be successfully treated with a low-
protein diet and dietary supplements
● The diet must be strictly followed
● Those who continue the diet into adulthood have better physical
and mental health.

25. PKU medication
The Food and Drug Administration (FDA) has approved the
drug sapropterin (Kuvan) for the treatment of PKU. It works
by increasing your tolerance to phenylalanine. The drug is
for use in combination with a PKU diet. But it doesn't work
for everyone with PKU.

26. Thank U!!!
Dr. V. MAGENDIRA MANI
Assistant Professor of Biochemistry
Islamiah College (Autonomous),
Vaniyambadi
magivbio@gmail.com; 9486000227