What is tetrahydrobiopterin deficiency?
Tetrahydrobiopterin deficiency results in abnormally elevated levels of phenylalanine (known as hyperphenylalaninemia) in various cells of the body including brain cells. Hyperphenylalaninemia can damage the affected cells, especially brain cells which are particularly sensitive to excess phenylalanine.
What is Ptps deficiency?
Definition. 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency is one of the causes of malignant hyperphenylalaninemia due to tetrahydrobiopterin deficiency.
What is Dhpr deficiency?
Dihydropteridine reductase deficiency (DHPR) is a severe form of hyperphenylalaninemia (high levels of the amino acid phenylalanine in the blood) due to impaired renewal of a substance known as tetrahydrobiopterin (BH4).
What is the role of tetrahydrobiopterin?
Tetrahydrobiopterin (BH4, THB), also known as sapropterin (INN), is a cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine ( …
How is BH4 deficiency treated?
Treatment of BH4 deficiencies consists of BH4 supplementation (2-20 mg/kg per day) or diet to control blood phenylalanine concentration and replacement therapy with neurotransmitters precausers (L-dopa/CarbiDOPA and 5-hydroxytryptophan), and supplements of folinic acid in DHPR deficiency.
What does Hyperphenylalaninemia mean?
Hyperphenylalaninemia is a hereditary metabolic disorder that causes elevated blood phenylalanine (Phe). Hyperphenylalaninemias are classified as Phenylketonuria PKU (Phe > 6 mg/dL) or mild hyperphenylalaninemia (mHPA) (Phe 2–6 mg/dL).
What does hyperphenylalaninemia mean?
Is Tetrahydrobiopterin a vitamin?
General information. Tetrahydrobiopterin is a naturally occurring nutrient and an essential co-factor of enzymes involved in the biosynthesis of 5-hydroxytryptamine (5HT, serotonin), dopamine, noradrenaline (norepinephrine), adrenaline (epinephrine), melatonin, and nitric oxide [1].
How do you test for BH4?
Diagnosis is based on the symptoms, clinical exam, and blood and urine tests. BH4 deficiency is sometimes diagnosed based on the results of an abnormal newborn screening test.
What is BH4 supplement?
BH4 Assist is an additional supplement choice for TRIAD 2 BRAIN/DEPRESSION support. BH4 plays a critical role in both neurotransmitter and nitric oxide production. It can be depleted by genetic polymorphisms in MTHFR A1298C, DHFR, high levels of ammonia (from CBS mutations), oxidative stress, or lack of SAMe or NADH.
How is Hyperphenylalaninemia diagnosed?
Hyperphenylalaninemia most is commonly diagnosed by newborn screening and must be distinguished from classic PKU by confirmatory testing at an experienced center. Some cases in adult women have been detected using maternal screening programs or following birth of children with birth defects.
How common is Hyperphenylalaninemia?
EPIDEMIOLOGY AND RISK FACTORS. Hyperphenylalaninemia due to BH4 deficiency is rare and accounts for 2% of all PKU cases.
What are the signs and symptoms of tetrahydrobiopterin deficiency?
The signs and symptoms of this condition can include: 1 intellectual disability, 2 progressive problems with development, 3 movement disorders, 4 difficulty swallowing, 5 seizures, 6 behavioral problems, and. 7 an inability to control body temperature.
What are the symptoms of benign hyperphenylalaninemia?
Benign hyperphenylalaninemia is considered an amino acid condition because people with benign hyperphenylalaninemia have problems breaking down an amino acid, a building block of proteins, known as phenylalanine. Most people with this condition experience mild symptoms or no symptoms.
What causes hyperphenylalanine encephalopathy in neonates?
Hyperphenylalaninemia causes a neonatal-onset chronic encephalopathy as a result of defects in phenylalanine metabolism, including phenylalanine hydroxylase (PAH) deficiency, tetrahydrobiopterin (BH 4) synthesis deficiency, and GTP cyclohydrolase (GTPC) deficiency.
What causes elevated tetrahydrobiopterin levels in the blood?
Tetrahydrobiopterin deficiency is a very rare disorder that increases the levels of several substances, including phenylalanine, in the blood. Most cases of elevated levels of phenylalanine in the blood are caused by a different condition known as phenylketonuria.
