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Phenylketonuria
Is phenylketonuria characterized only by pale facial skin?
Phenylketonuria is a common amino acid metabolic disorder. It is primarily due to the deficiency of phenylalanine hydroxylase, which prevents the conversion of phenylalanine to tyrosine, leading to a series of clinical symptoms. These can manifest as intellectual disability, neuropsychiatric symptoms, eczema, skin scratching, pigment loss, and a musty odor. The skin whiteness mentioned is not merely facial pallor; it affects the entire skin because the benefits of tyrosine are reduced, leading to decreased melanin synthesis. Consequently, the hair of affected children can also be lighter and tend to be brown.
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.
Does phenylketonuria cause liver dysfunction?
Phenylketonuria generally does not cause abnormalities in liver function. Phenylketonuria is a common amino acid metabolic disorder, mainly due to a deficiency of an enzyme in the phenylalanine metabolic pathway, preventing phenylalanine from being converted into tyrosine. This leads to the accumulation of phenylalanine and its keto acids, which are then excreted in large amounts in the urine. This disease is a relatively common genetic amino acid metabolic defect. Once diagnosed with phenylketonuria, the main treatment is a dietary therapy, which includes a low-phenylalanine diet. It is important during the upbringing of children to ensure that the child's living environment is quiet and comfortable. Therefore, in terms of prevention of the disease, it is important to avoid consanguineous marriage, conduct newborn screening, and focus on early detection and early treatment.
Does phenylketonuria affect intelligence?
Phenylketonuria is a common amino acid metabolic disease, primarily caused by a deficiency of phenylalanine hydroxylase in the metabolic pathway of phenylalanine, preventing phenylalanine from converting into tyrosine. This leads to the accumulation of phenylalanine and its ketones in the body, which are then excreted in large amounts through urine. Its clinical manifestations are not uniform. The main clinical characteristic is intellectual disability, thus it does affect intelligence. Additionally, it can present various neuropsychiatric symptoms such as increased muscle tone, hyperreflexia, agitation, hyperactivity, convulsions, etc. It can also lead to reduced skin pigmentation and yellowing of hair among other symptoms. This disease can impact intelligence.
How is phenylketonuria tested?
Phenylketonuria is a treatable inherited metabolic disease, and early diagnosis is essential for early treatment. Currently, we have generally implemented a newborn disease screening system that requires collecting peripheral blood by pricking the heel of newborns after three days of breastfeeding, dropping the blood onto specialized filter paper and sending it to a screening laboratory for phenylalanine concentration measurement. If the concentration exceeds the confirmed value, further differential diagnosis and confirmation are needed. If treatment can begin early, especially within two to three weeks after birth, the prognosis is generally good. Normally, the concentration is less than 120 µmol/L; a fetal concentration of 1200 µmol/L would be considered mild phenylketonuria.
Can patients with phenylketonuria eat fish and shrimp?
Children with phenylketonuria cannot eat fish and shrimp because phenylketonuria is caused by a deficiency of phenylalanine hydroxylase in the phenylalanine metabolic pathway, leading to metabolic disorder of phenylalanine in the liver. Phenylketonuria is the first hereditary metabolic disease that can be controlled by diet, as natural foods contain certain amounts of phenylalanine. Therefore, once diagnosed, children with phenylketonuria should stop consuming a natural diet and should be treated with a low phenylalanine diet. Fish and shrimp contain rich protein and high levels of phenylalanine, hence children with phenylketonuria cannot eat fish and shrimp.
What tests do parents with phenylketonuria undergo?
Parents with phenylketonuria can undergo chromosome testing. Phenylketonuria is a common amino acid metabolic disease and an autosomal recessive genetic disorder. Currently, it is mainly screened after the birth of the child by testing the blood for phenylketonuria. Phenylketonuria can also be screened prenatally before the birth of the newborn. Screening can be conducted by extracting amniotic fluid from the pregnant woman for genetic screening through amniocentesis between the 16th and 20th weeks of pregnancy. If chromosomal abnormalities are detected through amniocentesis, it indicates that the fetus carries the pathogenic gene, proving that the child will have phenylketonuria after birth. Couples carrying related genes also need to undergo prenatal screening.
When do people with phenylketonuria need to eat a special diet until?
Phenylketonuria is the first genetic metabolic disease that can be treated through dietary control. Since natural foods contain certain amounts of phenylalanine, once children with phenylketonuria are diagnosed, they should stop consuming a natural diet and start a low-phenylalanine diet treatment. 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, gradually small amounts of natural diet can be reintroduced. The food added should adhere to the principles of being low in protein and phenylalanine.
Can people with phenylketonuria not eat things high in protein?
Phenylketonuria patients should avoid foods high in protein, as phenylketonuria is a common amino acid metabolism disorder caused by a deficiency of phenylalanine hydroxylase in the metabolic pathway of phenylalanine, leading to disordered metabolism of phenylalanine in the liver. Phenylketonuria is a hereditary metabolic disease that can be managed through diet. Natural foods contain certain amounts of phenylalanine. Once diagnosed, the patient should cease consuming natural diets and switch to a phenylalanine-restricted diet. Foods rich in protein have higher amounts of phenylalanine, thus, those with phenylketonuria should not consume foods high in protein.
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.