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Mutations in the GCH1, PCBD1, PTS and QDPR genes directly cause BH4 deficiency. Additionally, mutations of the MTHFR gene (A1298C variant) and DHFR can interfere with the recycling of BH4 and lead to less severe, but still clinifically significant, deficiencies of BH4.
Autosomal dominant GTP cyclohydrolase I deficiency; Other names: Autosomal dominant Segawa syndrome (the autosomal recessive form of Segawa syndrome is caused by mutations in a different gene that encodes tyrosine hydroxylase), Dopa-responsive dystonia 5a, Autosomal dominant DYT/PARK-GCH1 (designation in accordance with the Nomenclature of Genetic Movement Disorders maintained by the ...
The transcribed protein is the first and rate-limiting enzyme in tetrahydrobiopterin (THB, BH 4) biosynthesis, catalyzing the conversion of GTP into 7,8-DHNP-3'-TP. THB is an essential cofactor required by the aromatic amino acid hydroxylase (AAAH) and nitric oxide synthase (NOS) enzymes in the biosynthesis of the monoamine neurotransmitters serotonin (5-hydroxytryptamine (5-HT)), melatonin ...
Tetrahydrobiopterin (BH 4, THB), also known as sapropterin (INN), [5] [6] is a cofactor of the three aromatic amino acid hydroxylase enzymes, [7] used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and is a cofactor for the ...
Dihydropteridine reductase deficiency (DHPRD) is a genetic disorder affecting the tetrahydrobiopterin (BH4) synthesis pathway, inherited in the autosomal recessive pattern. It is one of the six known disorders causing tetrahydrobiopterin deficiency , and occurs in patients with mutations of the QDPR gene.
Single-gene defects affecting the gene GCH1 block the first step in biopterin synthesis, and lead to dopamine-responsive dystonia, also known as Segawa's syndrome. This is due to the role of BH4 in synthesising neurotransmitters, including Dopamine, and is treated with supplementation with levodopa , which does not require BH4 for conversion to ...
A mutation in the gene GCH1, which encodes the enzyme GTP cyclohydrolase I, disrupts the production of BH4, decreasing dopamine levels (hypodopaminergia). This autosomal-dominant condition is the most frequent cause of dopamine-responsive dystonia. [ 1 ]
Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as an electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in one-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the DHFR gene. [5] [6] It is found in the q14.1 region of ...