how is pku inherited

How can you tell if you have PKU disease?

PKU symptom checker. For people with phenylketonuria (PKU), the symptoms of high or unstable blood phenylalanine (Phe) levels can occur slowly over time and can be difficult to recognize. Difficult for me to focus, difficult to maintain a PKU friendly Phe-restricted diet, forgetful, misplace things, need reminders, uncomfortable in groups, anxious when leaving the house, don’t understand ...

What is the average life expectancy of someone with PKU?

PKU does not shorten life expectancy, with or without treatment. Newborn screening for PKU is required in all 50 states. How long is the average life span of a person with PKU? The average age at death was 55.8 years. Eleven subjects were still alive (seven females and four males). The oldest living male was 79 years of age.

What is the inheritance pattern of PKU?

PKU is inherited in families in an autosomal recessive pattern. Autosomal recessive inheritance means that a person has two copies of the gene that is altered. Usually, each parent of an individual who has PKU carries one copy of the altered gene. Since each parent also has a normal gene, they do not show signs or symptoms of PKU.

What are the social effects of PKU?

• Abstract. Phenylketonuria (PKU) is a recessive disorder of phenylalanine metabolism due to mutations in the gene for phenylalanine hydroxylase (PAH).
• Introduction. ...
• Psychiatric Disorders. ...
• Cognition in PKU. ...
• Case Vignettes. ...
• Conclusions. ...
• Author Contributions. ...

How is PKU inherited explain?

PKU is inherited from a person's parents. The disorder is passed down in a recessive pattern, which means that for a child to develop PKU, both parents have to contribute a mutated version of the PAH gene. If both parents have PKU, their child will have PKU as well.

Can PKU be passed down?

How PKU is inherited. The genetic cause (mutation) responsible for PKU is passed on by the parents, who are usually carriers and do not have any symptoms of the condition themselves. The way this mutation is passed on is known as autosomal recessive inheritance.

Does PKU run in families?

Phenylketonuria (PKU) is passed down through families. To have the disease, a baby must get (inherit) the PKU gene from both parents. The father and mother may not have PKU or even know that PKU runs in their families.

Is PKU phenylketonuria dominant or recessive?

Classical PKU is an autosomal recessive disorder, caused by mutations in both alleles of the gene for phenylalanine hydroxylase (PAH), found on chromosome 12.

Is PKU more common in males or females?

The risk is the same for males and females. More than 300 different changes (mutations) in the PKU gene have been identified.

Who is most likely to get PKU?

In the United States, PKU is most common in people of European or Native American ancestry. It is much less common among people of African, Hispanic, or Asian ancestry.

How do you know if you are a carrier of PKU?

If you or your partner has PKU or is a PKU carrier, you can have a prenatal test to find out if your baby has PKU or is a carrier. You can have either of these tests: Chorionic villus sampling (also called CVS). This test checks tissue from the placenta for birth defects and genetic conditions.

How does a child get PKU?

PKU is caused by a defect in a gene known as the PAH gene. This defect changes the way that phenylalanine is broken down by the body during digestion. PKU is passed on to children when each parent has 1 mutated gene. This means that neither parent has any symptoms of PKU, but both are carriers of the faulty gene.

Can the PKU of a mother affect the fetus during pregnancy?

The maternal phenylketonuria (PKU) syndrome refers to the teratogenic effects of PKU during pregnancy. These effects include mental retardation, microcephaly, congenital heart disease, and intrauterine growth retardation.

Is PKU autosomal or Sexlinked?

Answer and Explanation: PKU is an autosomal recessive trait.

Is PKU heterozygous or homozygous?

In classic PKU patients, 58.4% were homozygous in comparison with only 11.1% in MHP patients. Mild PKU patients were 72.5% compound heterozygous in comparison with only 35.1% in classic PKU.

What is the life expectancy of someone with PKU?

PKU does not shorten life expectancy, with or without treatment. Newborn screening for PKU is required in all 50 states.

How is the family of a person with PKU affected?

Pregnancy and PKU: As PKU is inherited in an autosomal recessive fashion, all children of a mother with PKU will inherit 1 affected gene.

What precautions does a woman with PKU have to take when she decides to have a baby?

If I have PKU, what steps should I take during pregnancy to protect my infant? If you have PKU, it is very important to follow a strict low-phenylalanine diet before becoming pregnant and throughout your pregnancy. In addition to staying on a PKU diet, also make sure to: Visit a PKU clinic on a regular basis.

What do you do if PKU is positive?

If the first phenylalanine test demonstrates positive results, a repeat test should be performed. Treatment to prevent sequelae from this disorder is best carried out in cooperation with an experienced PKU center. Dietary care is expensive, and financial assistance may be necessary for many families.

What causes PKU?

A defective gene (genetic mutation) causes PKU, which can be mild, moderate or severe. In a person with PKU, this defective gene causes a lack of or deficiency of the enzyme that's needed to process phenylalanine, an amino acid. A dangerous buildup of phenylalanine can develop when a person with PKU eats protein-rich foods, such as milk, cheese, ...

What are the risk factors for inheriting PKU?

Risk factors for inheriting PKU include: Having both parents with a defective gene that causes PKU. Two parents must pass along a copy of the defective gene for their child to develop the condition.

Why is it important to maintain a PKU diet?

It's especially important for women with a history of PKU to see a doctor and maintain the PKU diet before becoming pregnant and during pregnancy to reduce the risk of high blood phenylalanine levels harming their unborn babies. Adults. People with PKU continue to receive care across the life span.

What is the name of the condition where a defect in the gene causes phenylalanine to build up

Phenylketonuria (fen-ul-key-toe-NU-ree-uh), also called PKU, is a rare inherited disorder that causes an amino acid called phenylalanine to build up in the body. PKU is caused by a defect in the gene that helps create the enzyme needed to break down phenylalanine.

How do you know if you have a PKU?

However, without treatment, babies usually develop signs of PKU within a few months. PKU signs and symptoms can be mild or severe and may include: A musty odor in the breath, skin or urine, caused by too much phenylalanine in the body.

What happens if you have high phenylalanine levels?

When mothers with PKU have high blood phenylalanine levels during pregnancy, fetal birth defects or miscarriage can occur. Untreated PKU can lead to: Irreversible brain damage and marked intellectual disability beginning within the first few months of life. Neurological problems such as seizures and tremors.

What is the most severe form of PKU?

The severity of PKU depends on the type. Classic PKU. The most severe form of the disorder is called classic PKU. The enzyme needed to convert phenylalanine is missing or severely reduced, resulting in high levels of phenylalanine and severe brain damage. Less severe forms of PKU.

How is PKU inherited?

PKU is inherited in families in an autosomal recessive pattern. Autosomal recessive inheritance means that a person has two copies of the gene that is altered. Usually, each parent of an individual who has PKU carries one copy of the altered gene. Since each parent also has a normal gene, they do not show signs or symptoms of PKU.

What is a PKU?

Symptoms of PKU range from mild to severe. Severe PKU is called classic PKU. Infants born with classic PKU appear normal for the first few months after birth. However, without treatment with a low-phenylalanine diet, these infants will develop mental retardation and behavioral problems.

What is PKU in medical terms?

What is phenylketonuria (PKU)? Phenylketonuria (PKU) is an inherited disorder of metabolism that causes an increase in the blood of a chemical known as phenylalanine. Phenylalanine comes from a person's diet and is used by the body to make proteins.

How is PKU diagnosed?

PKU is usually diagnosed through newborn screening testing that is done shortly after birth on a blood sample (heel stick). However, PKU should be considered at any age in a person who has developmental delays or mental retardation. This is because, rarely, infants are missed by newborn screening programs.

What does it mean when a person has two copies of the gene that is altered?

Autosomal recessive inheritance means that a person has two copies of the gene that is altered. Usually, each parent of an individual who has PKU carries one copy of the altered gene. Since each parent also has a normal gene, they do not show signs or symptoms of PKU.

Why is phenylalanine high in pregnancy?

Women who have high levels of phenylalanine during pregnancy are at high risk for having babies born with mental retardation, heart problems, small head size (microcephaly) and developmental delay. This is because the babies are exposed to their mother's very high levels of phenylalanine before they are born.

How many babies have PKU?

In the United States, PKU occurs in 1 in 10,000 to 1 in 15,000 newborn babies. Newborn screening has been used to detect PKU since the 1960's. As a result, the severe signs and symptoms of PKU are rarely seen.

What is the role of the NICHD in PKU?

Since its establishment, the NICHD has played a major role in PKU-related research. In the 1960s, federal Children's Bureau-supported researchers demonstrated the effectiveness of a PKU screening test that could easily and inexpensively screen for the disorder on a mass basis. Soon after, the NICHD led research on the safety and effectiveness of a restricted diet to treat PKU among newborns who had been identified using the screening test. As a result of the test and the Institute's follow-up research, PKU has been nearly eliminated as a cause of intellectual disabilities in the United States.

What is phenylketonuria?

Phenylketonuria (pronounced fen-l-kee-toh-NOOR-ee-uh ), often called PKU, is caused by phenylalanine hydroxylase (PAH) deficiency. It is an inherited disorder that that can cause intellectual and developmental disabilities (IDDs) if not treated. In PKU, the body can't process a portion of a protein called phenylalanine (pronounced fen-l-AL-uh-neen ), which is in all foods containing protein. High levels of phenylalanine can cause brain damage. PAH deficiency produces a spectrum of disorders, including PKU, non-PKU hyperphenylalaninemia, and variant PKU. Classic PKU is caused by a complete or near-complete deficiency of PAH.

Can you be missed with PKU?

In the United States, newborn screening identifies nearly all people born with PKU. 1 However, there are concerns that cases of PKU could be missed due to errors at any step of the screening process—specimen collection, laboratory procedures, treatment initiation, or clinical follow-up. Missed cases are considered to be extremely rare. Because of these rare cases, health professionals recommend PKU testing if a person of any age has developmental delays or an intellectual disability. 5

Why are babies born with PKU?

Babies born to mothers who have PKU and uncontrolled phenylalanine levels (women who no longer follow a low-phenylalanine diet) have a significant risk of intellectual disability because they are exposed to very high levels of phenylalanine before birth.

What is a PKU child?

Children with classic PKU tend to have lighter skin and hair than unaffected family members and are also likely to have skin disorders such as eczema. Less severe forms of this condition, sometimes called variant PKU and non-PKU hyperphenylalaninemia, have a smaller risk of brain damage.

What is the name of the disorder that increases the levels of a substance called phenylalanine in the

Phenylketonuria (commonly known as PKU) is an inherited disorder that increases the levels of a substance called phenylalanine in the blood. Phenylalanine is a building block of proteins ( an amino acid) that is obtained through the diet. It is found in all proteins and in some artificial sweeteners. If PKU is not treated, phenylalanine can build up to harmful levels in the body, causing intellectual disability and other serious health problems.

What is the cause of phenylketonuria?

Mutations in the PAH gene cause phenylketonuria. The PAH gene provides instructions for making an enzyme called phenylalanine hydroxylase. This enzyme converts the amino acid phenylalanine to other important compounds in the body. If gene mutations reduce the activity of phenylalanine hydroxylase, phenylalanine from the diet is not processed effectively. As a result, this amino acid can build up to toxic levels in the blood and other tissues. Because nerve cells in the brain are particularly sensitive to phenylalanine levels, excessive amounts of this substance can cause brain damage.

What are the medical problems associated with PKU?

Other characteristic medical problems include heart defects or other heart problems, an abnormally small head size ( microcephaly ), and behavioral problems. Women with PKU and uncontrolled phenylalanine levels also have an increased risk of pregnancy loss.

What happens if you don't treat PKU?

If PKU is not treated, phenylalanine can build up to harmful levels in the body, causing intellectual disability and other serious health problems. The signs and symptoms of PKU vary from mild to severe. The most severe form of this disorder is known as classic PKU. Infants with classic PKU appear normal until they are a few months old.

What is the most severe form of PKU?

The most severe form of this disorder is known as classic PKU. Infants with classic PKU appear normal until they are a few months old. Without treatment, these children develop permanent intellectual disability. Seizures, delayed development, behavioral problems, and psychiatric disorders are also common.

Is PKU inherited?

PKU is inherited from a person's parents. The disorder is passed down in a recessive pattern, which means that for a child to develop PKU, both parents have to contribute a mutated version of the PAH gene. If both parents have PKU, their child will have PKU as well.

Citations

NICHD. (2000, updated 2006). Report of the NIH consensus development conference on phenylketonuria (PKU): Screening and management. Retrieved May 15, 2012, from http://www.nichd.nih.gov/publications/pubs/pku/

What is PKU in newborn screening?

Inheritance is autosomal recessive manner. [1] [2] Because PKU can be detected by a simple blood test and is treatable, PKU is part of newborn screening. Treatment for PKU normally involves a phenyalanine-restricted diet ...

What is phenylketonuria?

Listen. Phenylketonuria (PKU) is a genetic metabolic disorder that increases the body's levels of phenylalanine. Phenylalanine is one of the building blocks ( amino acids) of proteins. Humans cannot make phenyalanine, but it is a natural part of the foods we eat.

What happens if you don't treat phenylalanine?

This means phenylalanine builds up in the person's blood, urine, and body. If PKU is not treated, phenylalanine can build up to harmful levels in the body. [1] [2] [3] PKU varies from mild to severe. The most severe form is known as classic PKU.

What is genetics materials for school success?

The Genetics Education Materials for School Success (GEMSS) aims to assure that all children with genetic health conditions succeed in school-life. Their Web site offers general and condition-specific education resources to help teachers and parents better understand the needs of students who have genetic conditions.

Does phenylalanine build up in the body?

However, people do not need all the phenyalanine they eat, so the body converts extra phenylalanine to another harmless amino acid, tyrosine. People with PKU cannot properly break down the extra phenylalanine to convert it to tyrosine. This means phenylalanine builds up in the person's blood, urine, and body.

What is PKU genetics?

PKU is an autosomal recessive metabolic genetic disorder. As an autosomal recessive disorder, two PKU alleles are required for an individual to experience symptoms of the disease. For a child to inherit PKU, both the mother and father must have and pass on the defective gene. If both parents are carriers for PKU, there is a 25% chance any child they have will be born with the disorder, a 50% chance the child will be a carrier, and a 25% chance the child will neither develop nor be a carrier for the disease.

What is PKU in biology?

Phenylketonuria ( PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders.

What is the pathophysiology of phenylketonuria?

Pathophysiology of phenylketonuria, which is due to the absence of functional phenylalanine hydroxylase (classical subtype) or functional enzymes for the recycling of tetrahydrobiopterin (new variant subtype) utilized in the first step of the metabolic pathway.

What is phenylalanine PKU?

Sapropterin dihydrochloride, pegvaliase. Prognosis. Normal health with treatment. Frequency. ~1 in 12,000 newborns. Phenylketonuria ( PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine.

What are the effects of PKU?

Untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also result in a musty smell and lighter skin. A baby born to a mother who has poorly treated PKU may have heart problems, a small head, and low birth weight. Phenylketonuria is a genetic disorder inherited from a person's parents.

How many babies are affected by phenylketonuria?

Phenylketonuria affects about 1 in 12,000 babies. Males and females are affected equally. The disease was discovered in 1934 by Ivar Asbjørn Følling, with the importance of diet determined in 1953. Gene therapy, while promising, requires a great deal more study as of 2014.

How to treat phenylalanine in babies?

Babies should use a special formula with a small amount of breast milk. The diet should begin as soon as possible after birth and be continued for life.

What is a PKU?

PKU is an autosomal recessive condition. What does that mean? Well, that means that people that have PKU have two recessive genes for the disorder. In scientific terms they are homozygous recessive for the PKU trait. The recessive gene which characterizes PKU is inherited from both parents.

What is heterozygous PKU?

Heterozygous is the biological term for a person that has one dominant gene for a trait and one recessive gene. In individuals that are heterozygous for PKU, the dominant gene completely masks the recessive one and the person displays no characteristics of the disorder. Say that "P" designates the dominant gene for the PKU condition, ...

What is the chance of a child being homozygous?

There is a 1 in 4 chance, or 25%, that the child will have a homozygous dominant genotype, a 2 in 4 chance, or 50%, that the child will have a heterozygous genotype and carry the PKU gene, and a 25% chance that the child will be homozygous recessive and have PKU.

What is the dominant gene in the left square?

In the left two squares the mother gives the offspring her dominant "P" gene, and in the right squares the recessive "p" gene. The result is three possible genetic combinations. In the upper left square, both parents supply the offspring with a dominant gene and the result is a child that has two dominant genes, homozygous dominant, ...

How many people are heterozygous for PKU?

Approximately one in 60 people in the United States is heterozygous for the PKU trait. For a person with PKU, their genotype is "p p", two recessive genes, and their phenotype is PKU. A Punnett square is a diagram of the possible offspring which could result from parents of designated genotype.

How many chances are there of having a PKU?

However, there is a 3 in 4 chance, or 75%, that the child will not have PKU. So, per pregnancy, there is a 25% chance of a PKU baby being born to heterozygous parents. In statistical terms, the chance of two heterozygous parents having one PKU child out of four is 42%. Many people believe that the odds of having one PKU child out of four is 25%.

Can a heterozygous child pass PKU on to their offspring?

The result is a heterozygous child who can pass PKU on to their offspring. In the lower left box the father supplies the child with a recessive gene and the mother supplies a dominant gene. The result is another heterozygous child.

Overview

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Symptoms

Causes

Risk Factors

Complications

Prevention