Symptoms of PKU may be mild or acute. Classic PKU is the most intense form of this disease. It is diagnosed a couple of days after an infant is born. The child may start to show signs of intellectual disabilities, stunted, growth, seizures, and eczema.
Because of routine screenings for PKU by doctors in the United States, the severity of classic PKU is hardly ever seen. It is identified soon after an infant is born and quickly treated.