Phenylketonuria - causes, symptoms, diagnosis, treatment, pathology

Summary

Phenylketonuria (PKU) is a rare genetic disorder caused by the buildup of phenylalanine, an essential amino acid, due to a deficiency in the enzyme phenylalanine hydroxylase. This condition can lead to severe neurological issues if untreated, including intellectual disability and seizures. Newborn screening is crucial for early detection, followed by a strict low-phenylalanine diet and specialized medical foods. Two FDA-approved treatments, Kuvan and Palynziq, can aid in managing PKU. Early intervention and individualized dietary plans are essential for improving outcomes and preventing complications associated with high phenylalanine levels.

Takeaways

• 🧬 Phenylketonuria (PKU) is a rare metabolic disorder caused by high levels of the amino acid phenylalanine in the blood.
• 🔬 PKU is an autosomal recessive genetic disorder affecting the enzyme phenylalanine hydroxylase, which converts phenylalanine into tyrosine.
• 👶 Newborns are routinely screened for PKU through a simple blood test taken 24 hours after birth.
• ⚠️ Untreated PKU can lead to severe intellectual disability, psychiatric disorders, and seizures.
• 🤰 Pregnant women with PKU must monitor their phenylalanine levels to reduce risks of Maternal PKU Syndrome in their babies.
• 🧠 High levels of phenylalanine can interfere with the transport of other amino acids across the blood-brain barrier, affecting brain function.
• 🥗 First-line treatment for PKU involves a low-phenylalanine diet that eliminates high-protein foods like meat, fish, and dairy.
• 💊 Two FDA-approved treatments for PKU are Kuvan, which enhances enzyme activity, and Palynziq, an injectable enzyme that helps metabolize phenylalanine.
• 🍏 Patients must customize their dietary intake of phenylalanine with the help of medical professionals based on individual needs.
• 🔄 Early intervention with treatment can significantly improve outcomes for individuals with PKU.

Q & A

What is phenylketonuria (PKU)?

PKU is a rare metabolic disorder caused by the accumulation of phenylalanine, leading to severe brain disorders.

Why is phenylalanine essential, and how do we obtain it?

Phenylalanine is one of the essential amino acids necessary for life, and it must be obtained through protein-rich foods because our bodies cannot produce it.

What role does the enzyme phenylalanine hydroxylase play in the body?

Phenylalanine hydroxylase converts phenylalanine into tyrosine, which is necessary for producing important neurotransmitters.

How is PKU inherited?

PKU is an autosomal recessive genetic disorder, meaning a child must inherit two copies of the mutated gene to develop the disease.

What are some symptoms of untreated PKU?

Untreated PKU can result in severe intellectual disability, psychiatric disorders, and seizures.

What risks does a pregnant woman with PKU face?

Pregnant women with PKU need to manage their phenylalanine levels to reduce the risk of Maternal PKU Syndrome, which can cause heart defects and developmental disabilities in the baby.

How does elevated phenylalanine affect the brain?

High levels of phenylalanine disrupt the transport of other amino acids like tyrosine and tryptophan across the blood-brain barrier, leading to decreased levels of crucial neurotransmitters.

How is PKU typically diagnosed?

PKU is usually diagnosed through newborn screening, where a blood sample is taken to measure phenylalanine levels.

What is the first-line treatment for PKU?

The first-line treatment for PKU is a low-phenylalanine diet, which includes medical foods and restrictions on high-protein foods.

What FDA-approved treatments are available for PKU?

Two FDA-approved treatments for PKU are Kuvan, which enhances enzyme activity, and Palynziq, an injectable enzyme that helps metabolize phenylalanine.