Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria (also known as BH4-deficient hyperphenylalaninemia) is a rare inherited disorder caused by a deficiency of the enzyme tetrahydrobiopterin (BH4). This enzyme is necessary for the production of certain neurotransmitters, including dopamine, serotonin, and norepinephrine. Without enough BH4, the body cannot properly break down the amino acid phenylalanine, leading to a buildup of phenylalanine in the blood (hyperphenylalaninemia). This can cause a variety of neurological and developmental problems, including intellectual disability, seizures, and behavioral problems. Treatment for this disorder involves taking a medication called sapropterin dihydrochloride (Kuvan) to replace the missing

The symptoms of Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria include:

-Developmental delay
-Seizures
-Behavioral problems
-Hyperactivity
-Impaired intellectual development
-Poor muscle tone
-Light skin and hair
-Musty body odor
-Abnormal movements
-Feeding difficulties
-Vomiting
-Diarrhea
-Lethargy
-Poor growth
-High levels of phenylalanine in the blood

Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria is caused by a deficiency of the enzyme tetrahydrobiopterin (BH4). This enzyme is responsible for the conversion of phenylalanine to tyrosine, and when it is deficient, phenylalanine accumulates in the body, leading to the symptoms of the disorder. The cause of the deficiency is usually a genetic mutation in the gene responsible for producing BH4.

The primary treatment for Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria is dietary management. This involves restricting the intake of phenylalanine, which is found in many foods, including dairy products, eggs, fish, meat, and nuts. Additionally, a synthetic form of tetrahydrobiopterin (BH4) may be prescribed to help the body process phenylalanine more efficiently. Other treatments may include vitamin and mineral supplements, as well as medications to reduce levels of phenylalanine in the blood.

1. Genetic mutation in the gene responsible for the production of the enzyme phenylalanine hydroxylase (PAH).

2. Deficiency of the cofactor tetrahydrobiopterin (BH4).

3. Exposure to certain environmental toxins, such as lead or mercury.

4. Maternal phenylketonuria (PKU).

5. Maternal diet high in phenylalanine.

6. Premature birth.

7. Low birth weight.

8. Family history of the disorder.

Yes, there is a cure for Tetrahydrobiopterin-responsive hyperphenylalaninemia/phenylketonuria. The primary treatment is a diet that is low in phenylalanine, which is an amino acid found in many foods. Additionally, medications such as sapropterin dihydrochloride (Kuvan) and tetrahydrobiopterin (BH4) can be used to help reduce the levels of phenylalanine in the blood.