Transcript Phenylketonuria (PKU)

PHENYLKETONURIA (PKU)
By Jessie Peterson
BIOLOGY OF PHENYLKETONURIA
 Phenylketonuria or PKU is the inability of the body to process and digest the
protein phenylaline
 Phenylaline builds to toxic levels in the tissues, particularly damaging the nervous
system
 PKU is a chronic disease, but it is possible to greatly reduce the probability of
further damage by following a strict low-protein diet
 PKU is autosomal recessive and carried on chromosome 12
SYMPTOMS OF PKU
 Mental disability
 Delayed development
 Behavioral, emotional, and social problems
 Psychiatric disorders
 Neurological problems, including seizures
 Hyperactivity
 Poor bone strength
 Eczema
Musty odor in breath, skin, or urine
 Fair skin and blue eyes (because phenylalanine
cannot transform into melanin)
Abnormally small head
Because high levels of phenylalanine
are particularly toxic to the nervous
system, many of the symptoms of PKU
are brain defects as a direct result of
this. This poisoning occurs early in the
patient’s life before diagnosis. Damage
before diagnosis cannot be undone, but
it can be stopped in it’s progression by
adapting to an extremely low protein
diet.
PKU AND PREGNANCY
Pregnant women with PKU must strictly adhere to treatments and a low-protein diet
or risk miscarriage or harm to the child. Even if the child does not inherit PKU, if the
mother is not extremely careful, the baby may have birth defects such as:
 Intellectual disability
Low birth weight
 delayed development
 abnormally small head
 heart defects
 behavioral problems
DIAGNOSING PKU
Every baby in the United States and several other countries are tested for PKU at
birth. The genetic tests administered are able to detect all but a few rare forms of
PKU. The rarer forms are tested for only if a parent or doctor expresses concern
upon viewing the symptoms of PKU in a young child.
RISK FACTORS
There is not a particular ethnicity or other biological or environmental factor that is
especially susceptible to PKU, although it has been noted that African Americans are
LESS likely to inherit or be a carrier of PKU. Basically, it’s luck of the draw that both
parents would be a carrier, and there are no predictable patterns to establish who is
particularly at risk.
STATISTICS OF PKU
 2% of the population are carriers of PKU
 PKU occurs in 1 in 10,000 to 15,000 newborns
 There are less than 20,000 US cases per year, making this disease very rare