Phenylketonuria: A Support Guide for Parents

Phenylketonuria: The birth defect that causes an amino acid to build up in the body.

Phenylketonuria, or PKU, is an inherited disorder that prevents the body from breaking down an amino acid called phenylalanine.

Most children born with this condition are normal. However, they develop signs and symptoms slowly over several months as phenylalanine builds up.

Diagnosis:

Children from families with a positive family history can be diagnosed before birth by direct mutation testing following chorionic villus sampling or amniocentesis.

It is also diagnosed through a simple blood test performed on all newborns.

Phenylketonuria is caused by one or more genetic mutations that result in a deficiency or absence of phenylalanine hydroxylase. Because of this, phenylalanine builds up in the diet; The brain is the main organ affected, perhaps due to impaired myelination.

Phenylketonuria can occur in all ethnic groups. Thus, inheritance is autosomal recessive; the incidence is approximately 1/10,000 births.

Treatment:

Treatment consists of a strict diet with limited amounts of protein.

Untreated, this disease can cause brain damage, intellectual disability, behavioral symptoms, or seizures. Therefore, laboratory tests or imaging studies are always required.

The degree of enzyme deficiency, and therefore the severity of hyperphenylalaninemia, varies among patients depending on the specific mutation.

Symptoms:

Children exhibit extreme hyperactivity.
Gait disturbance and psychosis.
They have an unpleasant, mouse-like body odor caused by phenylacetic acid in urine and sweat.
Children tend to have lighter skin, hair, and eye color than unaffected family members. • Some children develop a rash similar to childhood eczema.
If treatment is not started early, children may develop extreme hyperactivity and intractable seizures.

Consequences:

Slow growth, delayed development, developmental delay, or short stature.
Intellectual disability or slowness in performing activities.
Seizures, atopic dermatitis, bad body odor, bad urine odor, or loss of skin color.

Therefore, if phenylketonuria is not detected and treated early, excess phenylalanine can build up in the blood and cause serious brain damage. Therefore, it can lead to intellectual disability, seizures, and behavioral problems.