There is a recessive genetic cue that is silently influencing some people's lives, quietly lurking from infancy, through a common ingredient in the diet, quietly threatening a child's brain development: a rare genetic disease - phenylketonuria (PKU).
What is phenylketonuria?
Phenylketonuria is caused by a mutation in a gene called PAH, which causes a decrease or loss of activity in the body of a key enzyme responsible for converting an amino acid called phenylalanine into another amino acid — tyrosine. Phenylalanine is a building block of many proteins, and usually, we can ingest it through ordinary foods.
However, in the body of phenylketonuria, phenylalanine cannot be metabolized properly and begins to accumulate in the blood, eventually being converted into harmful substances. If left unchecked, these substances can cause damage to the brain and other organs, especially during infancy and early childhood.
What are the symptoms of phenylketonuria
1. Intellectual disability: If left untreated, high levels of phenylalanine can damage the brain, leading to decreased intelligence.
2. Behavioral problems: Hyperactivity, anxiety, depression, or other psychosocial problems may occur.
3. Epilepsy: The accumulation of phenylalanine can sometimes lead to epilepsy.
4. Skin problems: Skin symptoms such as eczema.
5. Delayed growth: Children may experience slower growth.
6. Microcephaly: This is when the head circumference is abnormally small.
7. Taste or smell: The patient's sweat, urine, and breath may have a specific sage-like smell due to the accumulation of phenylacetone in the body.
Due to the popularity of newborn screening programs, phenylketonuria can usually be diagnosed by newborn screening in infancy without obvious symptoms. Many of these symptoms can be prevented if treated with a low-phenylalanine diet early.
How phenylketonuria is treated
1. Low Phenylalanine diet:
Avoid high-protein foods such as meat, fish, eggs, milk and dairy products and nuts as they are high in phenylalanine.
Use special, low-protein foods such as low-protein bread and pasta.
Patients are given specially formulated phenylalanine replacement products that provide essential nutrients that do not contain phenylalanine, as well as other amino acids that the body needs for normal growth and health.
2. Amino Acid Supplements:
Supplements that contain all essential amino acids except phenylalanine can help ensure that patients are getting enough protein.
3. Medication:
Sapropterin is a synthetic form of the body's natural coenzyme 6R-tetrahydrobiopterin that can help some patients with PKU better metabolize phenylalanine.
Parquinone glutaramide (Pegvaliase-pqpz) is an enzyme replacement therapy used to treat PKU in adults.
4. Regular Monitoring:
Check your phenylalanine levels regularly to make sure they are staying within a safe range.
5. Genetic Counseling:
For patients with PKU who are planning to have a family plan, genetic counseling is important to understand the impact of the disease on the offspring and to take preventive measures.
6. Supportive Care:
Psychological support, especially for those who may be experiencing stress or anxiety due to dietary restrictions.
It is important to note that the treatment of PKU needs to be individualized, as phenylalanine is tolerated differently by each patient, and the diet and treatment regimen need to be adjusted according to the specific situation of the patient. In addition, pregnant women with PKU need to have very strict control of phenylalanine levels in their blood to prevent damage to the fetus.
How to prevent phenylketonuria
1. Newborn Screening:
Almost all newborns are screened for PKU, usually within 24-48 hours of birth.
Early diagnosis and treatment are essential to prevent PKU-related conditions.
2. Genetic Counseling:
If someone in the family has PKU, then intended parents can receive genetic counseling to find out if they are carriers and understand the risk of having a child with PKU.
A consultation can be given to find out how to test for a fetus with PKU through prenatal testing, such as amniocentesis or chorionic villus sampling.
3. Prenatal Screening and Diagnosis:
For couples with a known family history of PKU, genetic screening can be done before pregnancy to determine if they are both recessive carriers of PKU.
If both couples are carriers, they may choose to use assisted reproductive technologies, such as in vitro fertilization (IVF), in combination with embryo genetic diagnosis (PGD) to select embryos that do not carry the PKU mutation.
4. Pregnancy Management:
For women with PKU, even if her own PKU is well controlled, it is important to consult a specialist before planning pregnancy to ensure that low phenylalanine levels are maintained during pregnancy to avoid effects on the fetus.
Although phenylketonuria itself cannot be prevented, it can reduce the risk of serious complications in the affected child, or reduce the chance of birth through genetic counseling and prenatal diagnosis.
Phenylketonuria is a genetic disease that cannot be ignored, but through scientific treatment and management, we can effectively control its symptoms and reduce the impact of the disease on patients' lives. At the same time, we should also pay attention to the prevention and early diagnosis of PKU, and reduce the incidence and harm of PKU through genetic counseling and prenatal diagnosis.