Transcript PKU at a Glance

Phenylketonuria (PKU)
PKU at a Glance
Name
of disorder:
Phenylketonuria (PKU)
OMIM number: 261600
inheritance pattern: autosomal
recessive
PKU At A Glance
PKU
is a metabolic disorder
caused by a deficiency of the
liver enzyme phenylalanine
hydroxylase. It prevents normal
metabolization of
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.
PKU At A Glance
Untreated
individuals may give
off a musty odor and they
excrete large amounts of
phenylalanine in their urine.
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
Phe to Tyr Conversion
phenylalanine
hydroxylase,
which converts phenylalanine to
tyrosine.
Phe to Tyr Conversion
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.
Metabolic Pathways
Phenylalanine
builds up in the
body to toxic levels, causing
mental retardation.
PKU Genetics
The
PKU gene is found on the q
arm of chromosome 12, locus
24.1 in the phenylalanine
hydroxylase gene
PKU Genetics
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.
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.
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.
PKU Treatment
The
only treatment available for
PKU is a diet where
phenylalanine levels are strictly
limited.
PKU Treatment
Meat,
fish, eggs, cheese, milk
products, legumes, and bread
are all foods that have high
levels of phenylalanine
PKU Treatment
Artificial
protein substitutes are
given which contain amino
acids without phenylalanine
PKU Prognosis
If
the condition was not
diagnosed early and a special
diet started, the indidivudal will
suffer severe and irreversable
brain damage.
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.
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.