What are the main symptoms of hyperphenylalaninemia and phenylketonuria?


The symptoms of hyperphenylalaninemia are determined by two different enzymes: phenylalanine hydroxylase and alanine hydroxylase. Newborns who are deficient in phenylalanine hydroxylase and alanine hydroxylase are born without obvious symptoms, but develop symptoms after a few months. Growth retardation in patients with phenylketonuria. Neuropsychiatric and skin-hair symptoms.

Hyperphenylalaninemia is mainly due to an enzyme defect in the phenylalanine metabolic pathway, which increases blood phenylalanine levels. The blood phenylalanine concentration is higher than the blood phenylalanine and tyrosine ratio. Phenylketonuria is a common amino acid metabolic disease, mainly due to enzyme defects in the phenylalanine (p) metabolic pathway, so that phenylalanine cannot be converted into tyrosine, resulting in the accumulation of phenylalanine and its ketoacids. , and is excreted in the urine.

Hyperphenylalaninemia is mostly caused by genetic mutations, but the disease has two different genes and different symptoms.

1. Phenylalanine hydroxylase deficiency.

Patients with Phenylalanine Hydroxylase Deficiency have no obvious symptoms in the neonatal period, but their skin color will gradually lighten 3-4 months after birth. Hair turns yellow, and urine and sweat have a rat odor. With age, patients will gradually develop epilepsy, growth retardation, microcephaly and other symptoms.

2. Alanine hydroxylase deficiency.

Newborn patients with alanine hydroxylase deficiency are also asymptomatic. After 1-3 months of life, skin resembling phenylalanine hydroxylase deficiency develops. Changes in hair color and rat odor in urine. In addition, patients may experience symptoms such as insomnia, dyskinesia, increased salivation, lethargy, and unresponsiveness what is pku.


1. Growth retardation.

The main manifestation of growth retardation in phenylketonuria is mental retardation. The patient's intelligence will be significantly lower than that of normal children. This usually occurs between 4-9 months. Severe patients have an IQ below 50 and language is severely affected, indicating a developmental disorder of the brain.

2. Neuropsychiatry.

Phenylketonuria suffers from brain atrophy, leading to cerebellar malformations and recurrent convulsions. These symptoms decrease with age, but muscle tone increases. Symptoms of hyperreflexia often present with abnormal behavior.

3. Skin hair.

The patient's skin is often dry and prone to eczema and skin scratching. Due to the inhibition of tyrosinase, the synthesis of melanin is markedly reduced, resulting in a relatively light, brown hair color in patients.


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