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Tetrahydrobiopterin deficiency (THBD, BH 4 D) is a rare metabolic disorder that increases the blood levels of phenylalanine.Phenylalanine is an amino acid obtained normally through the diet, but can be harmful if excess levels build up, causing intellectual disability and other serious health problems.
The absence of BH 4 affects the metabolism of Phenylalanine. This is the reason that PKU and PTPS deficiency share some similar symptoms. However, since BH 4 is needed for much more than just the metabolism of Phenylalanine, there are other symptoms as well. [7]
It is a 4-hydroxyphenylpyruvate dioxygenase inhibitor indicated for the treatment of hereditary tyrosinemia type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine. [7] Liver transplant is indicated for patients with tyrosinemia type I who do not respond to nitisinone, as well as those with acute liver failure and ...
Hawkinsinuria is an autosomal dominant metabolic disorder affecting the metabolism of tyrosine. [1] [2] Normally, the breakdown of the amino acid tyrosine involves the conversion of 4-hydroxyphenylpyruvate to homogentisate by 4-hydroxyphenylpyruvate dioxygenase. Complete deficiency of this enzyme would lead to tyrosinemia III. In rare cases ...
Tyrosinemia type I is a genetic disorder that disrupts the metabolism of the amino acid tyrosine, resulting in damage primarily to the liver along with the kidneys and peripheral nerves. [1] The inability of cells to process tyrosine can lead to chronic liver damage ending in liver failure , as well as renal disease and rickets .
Type II tyrosinemia is caused by a deficiency of the enzyme tyrosine aminotransferase (EC 2.6.1.5), encoded by the gene TAT.Tyrosine aminotransferase is the first in a series of five enzymes that converts tyrosine to smaller molecules, which are excreted by the kidneys or used in reactions that produce energy.
Tyrosinemia type III is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27), encoded by the gene HPD. [2] This enzyme is abundant in the liver, and smaller amounts are found in the kidneys. It is one of a series of enzymes needed to break down tyrosine.
Tetrahydrobiopterin (BH 4, THB), also known as sapropterin (), [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 ...