Question
What are the early symptoms of phenylketonuria?
Answer
- Early symptoms may include neurological abnormalities such as restlessness, hyperactivity, decreased appetite, and lethargy. In rare cases, increased muscle tone, hyperactive reflexes, and seizures (about 25%) may occur, followed by increasingly evident delayed intellectual development with 80% showing abnormal EEGs. The neurological symptoms in BH4 deficiency are usually earlier and more severe, often characterized by reduced muscle tone, decreased appetite, and seizures. Without treatment, children often die in childhood.
- Due to insufficient melanin production, hair, skin, and iris color may lighten within a few months after birth. The skin may become dry and may be accompanied by eczema. Phenylacetic acid is excreted in urine and sweat, emitting a characteristic smell of mouse urine.