Phenylketonuria inheritance mode

Written by Hu Qi Feng

Pediatrics

Updated on September 01, 2024

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Phenylketonuria is an autosomal recessive genetic disorder, caused by a mutation in the phenylalanine hydroxylase gene leading to reduced enzyme activity. This results in the accumulation of phenylalanine and its metabolic products in the body, causing the disease. It is the most common congenital amino acid metabolism disorder and is clinically characterized by delayed intellectual development, changes in skin and hair pigmentation, and a mousy urine odor. The incidence of this disease in China is approximately 1 in 11,000, and it is inherited in an autosomal recessive manner.

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Written by Yan Xin Liang

Pediatrics

1min 16sec

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Phenylketonuria is a disease.

Phenylketonuria is an autosomal recessive genetic disorder resulting from mutations in the phenylalanine hydroxylase gene, leading to reduced enzyme activity and the accumulation of phenylalanine and its metabolic products in the body, thereby causing this disease. Phenylketonuria is the most common congenital amino acid metabolic disorder, clinically characterized by intellectual developmental delays, light skin and hair pigmentation, and a mouse-like urine odor. The incidence of the disease varies by race and region, with an incidence rate in China of about 1 in 11,000. Phenylalanine is an essential amino acid for the human body, but due to reduced activity of phenylalanine hydroxylase, phenylalanine cannot be converted into tyrosine, leading to extremely high concentrations of phenylalanine in the blood, cerebrospinal fluid, and tissues. Abnormal metabolism produces a large amount of phenylpyruvic acid, phenylacetic acid, phenyllactic acid, and p-hydroxyphenylacetic acid, along with high concentrations of phenylalanine and its metabolic products, causing brain damage and corresponding symptoms.

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Written by Zeng Hai Jiang

Pediatrics

52sec

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Do adults with phenylketonuria need to eat special food?

Phenylketonuria may not necessarily require a special diet in adulthood. It is the first genetic metabolic disorder that can be treated through dietary control. Natural foods all contain a certain amount of phenylalanine, so once children with phenylketonuria are diagnosed, they should stop their natural diet and instead be given a low-phenylalanine diet. Low-phenylalanine formula treatment should continue at least until the age of 12. When the concentration of phenylalanine in the blood is controlled at an ideal level, a gradual addition of natural foods can be made. Larger infants and children can add foods such as milk, porridge, noodles, and eggs. However, these added foods should still primarily be low in protein and low in phenylalanine.

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Written by Yan Xin Liang

Pediatrics

38sec

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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 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

1min 34sec

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The causes of phenylketonuria

Phenylketonuria is a common autosomal recessive genetic disorder, the most frequent primary clinical manifestation among congenital amino acid metabolic disorders. It is characterized by intellectual disability, pale skin and hair pigmentation, and a mouse urine-like odor. The main cause is that phenylalanine is an essential amino acid for the human body. The phenylalanine ingested is partly used for protein synthesis and partly converted to tyrosine by the action of phenylalanine hydroxylase, which is necessary for the synthesis of substances like adrenaline, melanin, and thyroxine. The disease is mainly due to a deficiency of phenylalanine hydroxylase, which inhibits the conversion of phenylalanine to tyrosine, resulting in increased concentrations of phenylalanine in the blood, cerebrospinal fluid, and various tissues. At the same time, due to the predominance of the main pathway, the enhancement of the secondary metabolic pathway leads to the deamination of phenylalanine by transaminase, producing a large amount of phenylpyruvic acid, which through oxidation produces a large amount of phenylacetic acid, phenyllactic acid, and p-hydroxyphenylpyruvic acid. These metabolic by-products are excreted in large quantities in the urine, and the high concentrations of phenylalanine and its by-products accumulate extensively in brain tissue, thereby causing damage to brain cells.