Phenylketonuria is what type of inheritance?

Written by Yan Xin Liang
Pediatrics
Updated on May 15, 2025
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Phenylketonuria is an autosomal recessive genetic disorder and is the most common congenital amino acid metabolism disorder. The main clinical features include intellectual disability, pale skin and hair pigmentation, and a mouse-like urine smell. This condition is named after the high levels of phenylketonic acid metabolites excreted in the urine of affected patients. Phenylketonuria is an autosomal recessive genetic disease, and its primary pathological mechanism is due to the lack of phenylalanine hydroxylase, which fails to convert phenylalanine into tyrosine, leading to increased concentrations of phenylalanine in the blood, cerebrospinal fluid, and various tissues. Because the main metabolic pathway is blocked, secondary metabolic pathways are enhanced, leading to the deamination of phenylalanine and the production of large amounts of phenylketonic acid. Through oxidation, this produces byproducts such as phenylacetic acid, phenyllactic acid, and para-hydroxyphenylketonic acid, thereby resulting in a series of clinical symptoms.

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Written by Zeng Hai Jiang
Pediatrics
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Can phenylketonuria cause hair to turn white?

Phenylketonuria is caused by a mutation in the phenylalanine hydroxylase gene, resulting in reduced or lost enzyme activity, and a metabolic disorder of phenylalanine in the liver. Children with phenylketonuria lack phenylalanine hydroxylase, leading to reduced tyrosine and normal metabolic products. The content of phenylalanine in the blood increases, secondary metabolic pathways are enhanced, producing phenylpyruvic acid, phenylacetic acid, and phenyllactic acid, which are excreted in large amounts in the urine. High concentrations of phenylalanine and its abnormal metabolic products inhibit tyrosinase, leading to disturbances in melanin synthesis. Therefore, untreated children will gradually show changes in hair color from black to yellow and skin lightening after three months.

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Written by Yao Li Qin
Pediatrics
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Phenylketonuria should be treated in which department?

Phenylketonuria is a common autosomal recessive genetic disorder due to a deficiency in the enzymes involved in the metabolic pathway of phenylalanine. It is a genetic metabolic disease. After the birth of a child, newborn screening is conducted for this disease. If a child is diagnosed with phenylketonuria or suspected of having the condition, it is common to visit a pediatric neurology department at a children's hospital. Phenylketonuria mainly causes varying degrees of intellectual disability, and some children may even experience epileptic seizures. Additionally, about 90% of affected children gradually develop lighter skin and hair, reduced iris pigmentation, dry skin, eczema, and a distinctive mouse-like urine odor, which is due to the excretion of phenylacetic acid in urine and sweat. It is a challenging genetic metabolic disorder to treat, requiring special dietary management. It is advisable to bring the child to the pediatric neurology department. Some hospitals may have a specialized department for genetic metabolic diseases. If such a department is available, it is recommended to consult there; otherwise, pediatric neurology is the appropriate alternative.

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Written by Zeng Hai Jiang
Pediatrics
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Can people with phenylketonuria eat meat?

Children with phenylketonuria should not eat meat and should try to eat as little as possible. Phenylketonuria is caused by a defect in the phenylalanine hydroxylase enzyme in the phenylalanine metabolic pathway, which results in a metabolic disorder of phenylalanine in the liver. Phenylketonuria is the first hereditary metabolic disease that can be treated by dietary control. All natural foods contain a certain amount of phenylalanine. Once diagnosed, children should stop consuming a natural diet and be given a low-phenylalanine diet for treatment. Meat is rich in protein and also contains a high amount of phenylalanine, thus the intake of meat must be restricted or minimized.

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Written by Yan Xin Liang
Pediatrics
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Phenylketonuria positive means what?

Phenylketonuria is an autosomal recessive inherited disease and is the most common congenital amino acid metabolism disorder. Generally, if the activity of phenylalanine hydroxylase in the body is reduced, or if there is a deficiency in its coenzyme tetrahydrobiopterin, the concentration of phenylalanine in the blood and tissues will increase, and phenylpyruvic acid, phenylacetic acid, and phenyllactic acid in the urine will also increase. Generally, newborns may not show any special clinical features at first. Often, the first test results may be high due to maternal influence or dietary factors, which can cause these elevated indicators in newborns. If the second test is normal, there usually isn’t a significant problem. A third test can also be performed; if the third test still shows no issues, then phenylketonuria can be ruled out. Generally, if phenylketonuria is diagnosed, it should be treated promptly and properly.

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Written by Zeng Hai Jiang
Pediatrics
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Can phenylketonuria eat corn?

People with phenylketonuria can eat corn. Phenylketonuria is a hereditary metabolic disease that can be treated through dietary control. Once diagnosed with phenylketonuria, one must stop a natural diet and switch to a low-phenylalanine diet. When the concentration of phenylalanine in the blood drops to an ideal level, natural foods can be gradually reintroduced in small amounts, but the diet must still adhere to low-protein and low-phenylalanine standards. Corn mainly consists of starch and does not contain phenylalanine, so individuals with phenylketonuria can eat corn.