Phenylketonuria: Difference between revisions
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{{Infobox medical condition | |||
[[File:L-Phenylalanin_-_L-Phenylalanine.svg| | | name = Phenylketonuria | ||
| image = [[File:L-Phenylalanin_-_L-Phenylalanine.svg|alt=Chemical structure of phenylalanine]] | |||
| caption = Chemical structure of [[phenylalanine]] | |||
| synonyms = PKU | |||
| pronounce = | |||
| specialty = [[Medical genetics]] | |||
| symptoms = Intellectual disability, seizures, behavioral problems, mental disorders, musty smell | |||
| onset = Symptoms develop gradually | |||
| duration = Lifelong | |||
| causes = [[Genetic mutation]] in the [[PAH (gene)|PAH gene]] | |||
| risks = Family history | |||
| diagnosis = [[Newborn screening]], [[blood test]] | |||
| differential = [[Hyperphenylalaninemia]], [[biopterin deficiency]] | |||
| prevention = [[Dietary management]] | |||
| treatment = [[Low-phenylalanine diet]], [[sapropterin]] | |||
| medication = [[Sapropterin]], [[pegvaliase]] | |||
| prognosis = Good with treatment | |||
| frequency = 1 in 12,000 births | |||
| deaths = Rare with treatment | |||
}} | |||
'''Phenylketonuria''' ('''PKU''') is a rare [[genetic disorder]] characterized by the inability to metabolize the amino acid [[phenylalanine]]. This condition is caused by a deficiency in the enzyme [[phenylalanine hydroxylase]], which is necessary for converting phenylalanine to [[tyrosine]]. | '''Phenylketonuria''' ('''PKU''') is a rare [[genetic disorder]] characterized by the inability to metabolize the amino acid [[phenylalanine]]. This condition is caused by a deficiency in the enzyme [[phenylalanine hydroxylase]], which is necessary for converting phenylalanine to [[tyrosine]]. | ||
== Genetics == | == Genetics == | ||
[[File:Autorecessive.svg|left|thumb|Autosomal recessive inheritance pattern]] | |||
[[File:Autorecessive.svg|thumb | |||
PKU is inherited in an [[autosomal recessive]] pattern, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected by the disorder. The gene responsible for PKU is located on chromosome 12. | PKU is inherited in an [[autosomal recessive]] pattern, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected by the disorder. The gene responsible for PKU is located on chromosome 12. | ||
== Pathophysiology == | == Pathophysiology == | ||
In individuals with PKU, the accumulation of phenylalanine in the body can lead to a variety of health problems. High levels of phenylalanine can cause damage to the [[brain]] and [[nervous system]], leading to intellectual disability and other neurological issues. | In individuals with PKU, the accumulation of phenylalanine in the body can lead to a variety of health problems. High levels of phenylalanine can cause damage to the [[brain]] and [[nervous system]], leading to intellectual disability and other neurological issues. | ||
== Clinical Features == | == Clinical Features == | ||
[[File:NIH_microcephaly.jpg|left|thumb|Microcephaly is a possible feature of untreated PKU]] | |||
[[File:NIH_microcephaly.jpg|thumb | |||
Symptoms of PKU can vary but often include intellectual disability, [[microcephaly]], [[seizures]], and behavioral problems. If untreated, PKU can lead to severe developmental delays and neurological complications. | Symptoms of PKU can vary but often include intellectual disability, [[microcephaly]], [[seizures]], and behavioral problems. If untreated, PKU can lead to severe developmental delays and neurological complications. | ||
== Diagnosis == | == Diagnosis == | ||
[[File:Phenylketonuria_testing.jpg|left|thumb|Newborn screening for PKU]] | |||
[[File:Phenylketonuria_testing.jpg|thumb | |||
PKU is typically diagnosed through [[newborn screening]] programs, which test for elevated levels of phenylalanine in the blood. Early detection is crucial for preventing the adverse effects of the disorder. | PKU is typically diagnosed through [[newborn screening]] programs, which test for elevated levels of phenylalanine in the blood. Early detection is crucial for preventing the adverse effects of the disorder. | ||
== Treatment == | == Treatment == | ||
The primary treatment for PKU is a [[phenylalanine-restricted diet]], which involves limiting the intake of foods high in phenylalanine, such as meat, dairy, and nuts. Special medical formulas and foods are often used to ensure adequate nutrition while maintaining low phenylalanine levels. | The primary treatment for PKU is a [[phenylalanine-restricted diet]], which involves limiting the intake of foods high in phenylalanine, such as meat, dairy, and nuts. Special medical formulas and foods are often used to ensure adequate nutrition while maintaining low phenylalanine levels. | ||
== Complications == | == Complications == | ||
If PKU is not managed properly, individuals may experience severe intellectual disability, behavioral problems, and other neurological issues. Pregnant women with PKU must maintain strict control of their phenylalanine levels to prevent [[maternal PKU syndrome]], which can affect the developing fetus. | If PKU is not managed properly, individuals may experience severe intellectual disability, behavioral problems, and other neurological issues. Pregnant women with PKU must maintain strict control of their phenylalanine levels to prevent [[maternal PKU syndrome]], which can affect the developing fetus. | ||
== Prevention == | == Prevention == | ||
[[File:Phenylalanine_warning_for_phenylketonurics.jpg|left|thumb|Warning label for phenylketonurics]] | |||
[[File:Phenylalanine_warning_for_phenylketonurics.jpg|thumb | |||
Genetic counseling is recommended for families with a history of PKU. Prenatal testing and carrier screening can help identify at-risk pregnancies and individuals. | Genetic counseling is recommended for families with a history of PKU. Prenatal testing and carrier screening can help identify at-risk pregnancies and individuals. | ||
== See also == | |||
== | |||
* [[Inborn errors of metabolism]] | * [[Inborn errors of metabolism]] | ||
* [[Amino acid metabolism]] | * [[Amino acid metabolism]] | ||
* [[Genetic disorders]] | * [[Genetic disorders]] | ||
[[File:Inborn_errors_of_metabolism_of_phenylalanine_and_tyrosine.svg|left|thumb|Metabolic pathway of phenylalanine and tyrosine]] | |||
[[File:Inborn_errors_of_metabolism_of_phenylalanine_and_tyrosine.svg|thumb | |||
== See Also == | == See Also == | ||
* [[Tyrosinemia]] | * [[Tyrosinemia]] | ||
* [[Alkaptonuria]] | * [[Alkaptonuria]] | ||
* [[Maple syrup urine disease]] | * [[Maple syrup urine disease]] | ||
[[Category:Genetic disorders]] | [[Category:Genetic disorders]] | ||
[[Category:Metabolic disorders]] | [[Category:Metabolic disorders]] | ||
[[Category:Autosomal recessive disorders]] | [[Category:Autosomal recessive disorders]] | ||
Revision as of 12:17, 12 April 2025
Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD's medical weight loss NYC, sleep center NYC
Philadelphia medical weight loss and Philadelphia sleep clinics
| Phenylketonuria | |
|---|---|
| |
| Synonyms | PKU |
| Pronounce | |
| Specialty | Medical genetics |
| Symptoms | Intellectual disability, seizures, behavioral problems, mental disorders, musty smell |
| Complications | N/A |
| Onset | Symptoms develop gradually |
| Duration | Lifelong |
| Types | N/A |
| Causes | Genetic mutation in the PAH gene |
| Risks | Family history |
| Diagnosis | Newborn screening, blood test |
| Differential diagnosis | Hyperphenylalaninemia, biopterin deficiency |
| Prevention | Dietary management |
| Treatment | Low-phenylalanine diet, sapropterin |
| Medication | Sapropterin, pegvaliase |
| Prognosis | Good with treatment |
| Frequency | 1 in 12,000 births |
| Deaths | Rare with treatment |
Phenylketonuria (PKU) is a rare genetic disorder characterized by the inability to metabolize the amino acid phenylalanine. This condition is caused by a deficiency in the enzyme phenylalanine hydroxylase, which is necessary for converting phenylalanine to tyrosine.
Genetics
PKU is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected by the disorder. The gene responsible for PKU is located on chromosome 12.
Pathophysiology
In individuals with PKU, the accumulation of phenylalanine in the body can lead to a variety of health problems. High levels of phenylalanine can cause damage to the brain and nervous system, leading to intellectual disability and other neurological issues.
Clinical Features
Symptoms of PKU can vary but often include intellectual disability, microcephaly, seizures, and behavioral problems. If untreated, PKU can lead to severe developmental delays and neurological complications.
Diagnosis
PKU is typically diagnosed through newborn screening programs, which test for elevated levels of phenylalanine in the blood. Early detection is crucial for preventing the adverse effects of the disorder.
Treatment
The primary treatment for PKU is a phenylalanine-restricted diet, which involves limiting the intake of foods high in phenylalanine, such as meat, dairy, and nuts. Special medical formulas and foods are often used to ensure adequate nutrition while maintaining low phenylalanine levels.
Complications
If PKU is not managed properly, individuals may experience severe intellectual disability, behavioral problems, and other neurological issues. Pregnant women with PKU must maintain strict control of their phenylalanine levels to prevent maternal PKU syndrome, which can affect the developing fetus.
Prevention
Genetic counseling is recommended for families with a history of PKU. Prenatal testing and carrier screening can help identify at-risk pregnancies and individuals.
See also
