Does phenylketonuria require a lifetime of special milk consumption?

Written by Zeng Hai Jiang

Pediatrics

Updated on November 22, 2024

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Phenylketonuria does not require a lifetime of special milk consumption. It is the first genetically inherited metabolic disorder that can be treated through dietary control. Once diagnosed with phenylketonuria, one must stop a natural diet and begin treatment with a low-phenylalanine diet. The low-phenylalanine milk formula should be consumed at least until the age of 12. When the concentration of phenylalanine in the blood is controlled within the ideal range, it is possible to appropriately add a small amount of natural diet, adhering to principles of low protein and low phenylalanine.

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Written by Yan Xin Liang

Pediatrics

47sec

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What is the probability of phenylketonuria?

Phenylketonuria is an autosomal recessive genetic disorder primarily caused by mutations in the phenylalanine hydroxylase gene, leading to reduced enzyme activity and the accumulation of phenylalanine and its metabolites in the body, resulting in the disease. Phenylketonuria is the most common congenital amino acid metabolism disorder, with clinical manifestations mainly including intellectual developmental delays, light skin and hair pigmentation, and a mouse urine odor. The incidence of the disease varies by race and region. In China, the incidence of phenylketonuria is approximately 1 in 11,000, meaning that about one in 11,000 children suffers from phenylketonuria.

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Written by Yan Xin Liang

Pediatrics

59sec

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What is the normal value for phenylketonuria?

Phenylketonuria is a common autosomal recessive genetic disorder and the most common congenital amino acid metabolism disorder. It primarily manifests as intellectual disability, light skin and hair pigmentation, and a mousey urine odor. Newborn screening includes routine screening for phenylketonuria as it is a treatable hereditary metabolic disorder, emphasizing the importance of early diagnosis and treatment. Nowadays, newborn screening systems are widely implemented. Generally, this involves collecting a blood sample through a heel prick, dropping the blood on specialized filter paper, and then air drying before sending it to a screening laboratory to measure the phenylalanine concentration. Typically, a normal concentration should be less than 120 micromoles per liter. If the phenylalanine concentration exceeds 1200 micromoles per liter, it can be diagnosed as classical phenylketonuria.

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Written by Yan Xin Liang

Pediatrics

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Is the incidence of phenylketonuria high?

Phenylketonuria is an autosomal recessive hereditary disease and is the most common congenital amino acid metabolic disorder. The main clinical manifestations include distinctive features such as intellectual disability, light skin and hair pigmentation, and a mouse-like urine odor, which is named after the large amounts of phenylketone acid metabolites excreted in the urine. The incidence of this disease varies by race and region, and the overall incidence in China is approximately 1:11,000, meaning one in eleven thousand. The incidence is higher in the northern population than in the southern population, though it is not particularly high.

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Written by Zeng Hai Jiang

Pediatrics

1min 2sec

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Does phenylketonuria require lifelong dietary control?

Theoretically, phenylketonuria requires lifelong dietary control. Phenylketonuria is caused by a deficiency in phenylalanine hydroxylase in the metabolic pathway of phenylalanine, leading to disordered metabolism of phenylalanine in the liver. Phenylketonuria is the first genetic metabolic disease that can be managed through diet. Since natural foods all contain certain amounts of phenylalanine, once diagnosed, affected children should cease consuming natural diets and should be treated with a low-phenylalanine diet. Treatment with a low-phenylalanine formula should continue at least until the age of 12. When the concentration of phenylalanine in the blood is controlled at an ideal level, natural foods can gradually be reintroduced in small amounts. The reintroduction of food should still follow the principles of low protein and low phenylalanine. The types and amounts of food that each child can add vary individually and are related to the severity of the enzyme deficiency.

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Written by Yan Xin Liang

Pediatrics

52sec

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Clinical symptoms of phenylketonuria

The clinical symptoms of phenylketonuria generally include normal appearance at birth, with symptoms usually appearing between three to six months, and becoming more pronounced by the age of one. The most noticeable initial symptoms involve the nervous system; delayed intellectual development is prominent, with intelligence often below normal, along with behavioral abnormalities such as hyperactivity, depression, restlessness, and withdrawal. There could be minor epileptic seizures, and in some cases, increased muscle tone or exaggerated tendon reflexes. Regarding the skin, several months after birth, due to insufficient melanin synthesis, the child’s hair changes from black to yellow, the skin appears pale, and eczema is also relatively common. Additionally, the urine and sweat contain higher levels of phenylacetic acid, which can result in a distinctive mouse-like urine odor.