There are 5 symptoms of phenylketonuria

Phenylketonuria is a common disease in daily life, which is mainly caused by abnormal amino acid metabolism. Most patients begin to show symptoms within 3-6 months. Therefore, it is important to understand the symptoms of phenylketonuria in a timely manner and receive early treatment to minimize the impact of the disease on the baby's healthy development.

Clinical manifestations:

The affected children are normal at birth, and symptoms usually begin to appear at 3 to 6 months, and become obvious at 1 year old.

1. Mental retardation: It is the main symptom of this disease. If not treated in time, the child may show sluggish expression and delayed intellectual development a few months after birth. 60% of the children have severe mental retardation, and only 2-4% have close to normal intelligence. The child has developmental and speech delays. Without treatment, half of children have an IQ < 50°

2. Epileptic seizures: more common in children under 1 year old and those with severe intellectual disabilities. It may manifest as infantile spasms or other types. EEG may show abnormalities such as high-peak rhythm disorders and focal spikes.

3. Appearance: The hair color is normal at birth. In 90% of the sick children, the hair, skin and iris color become lighter a few months after birth due to insufficient melanin synthesis.

4. Urine and sweat: The levels of phenylalanine, phenylpyruvate, phenyllactic acid and phenylacetic acid in urine increase, and the urine has a rat urine odor.

5. Others: Vomiting and skin eczema are common.

There are three types: classic type (infant and children type), malignant type and transient type.

The classic type is severe mental retardation after 3 months, with speech disorders being the most serious. 85% are idiots, with high or low muscle tone, inability to sit or walk, pyramidal tract signs, and often facial eczema. At the age of 1, the skin is fair with light yellow hair, the irises are yellowish or light blue, and the urine has a special musty or rat smell. After the age of 2, children often have convulsions, hyperactivity, enlarged and protruding maxilla, widened maxillary tooth distance, slow height development, and loneliness and introversion.

1-3% of children with classic type develop severe brain damage at the age of 1, which is called malignant hyperphenylalaninosis.

The other is transient or benign hyperphenylalaninemia, which does not require treatment.