Treatment of type I tyrosinemia is –
Correct Answer: Niiisinone
Description: Ans. is 'a' i.e., Nitisinoneo Tyrosine is an aromatic amino acid important in the synthesis of thyroid hormone, catecholamines, and melanin. Impaired caiabolism of tyrosine is a feature of several acquired and genetic disorders that may result in elevated plasma tyrosine concentrations.Tyrosine metabolismo Tyrosine degradation is catalyzed by a series of five enzymatic reactions thatyiel acetaacetate, which is ketogenic, and the Krebs cycle intermediate fumarate, which is glucogenic.o The hepatocvte and renal proximal tubules are the only two cell types that express the complete pathway and contain sufficient quantities of all enzymes required for tyrosine catabolism.o Four autosomal recessive disorders result from deficiencies in specific enzymes in the tyrosine catabolic pathway.Hereditary tyrosinemia (HT) types 1,2, and 3,Alkaptonuria (AKU).o Except for AKU, these disorders result in elevated blood tyrosine levels.Hvpertvrosinemiao Normal plasma tyrosine concentration are 30 to 120 micromol/L.o Values > 200 micromol/L are considered elevated.o However, clinical manifestations typically do not become apparent until plasma levels exceed 500 micromol/L.Hereditary Tyrosinemia type 1o Hereditary tyrosinemia type 1, also known as hepatorenal tyrosinemia, is the most severe disorder of tyrosine metabolism.o HT1 is caused by deficiency-1 of fumarydacetoacetate hydrolase (FAH), the last enzyme in the pathway of tyrosine catabolism.o Fumarylacetoacetate (FAA), the substrate for FAH in the tyrosine pathway, accumulates in FAH-deficient hepatocytes and proximal renal tubular cells, resulting in liver and kidney damage.HT1 managemento Dietary treatment, consisting of foods with low or absent phenylalanine, tyrosine, methionine, and restriction of natural protein, results in decreased tyrosine levels.o However, this approach does not stop the production of SA, prevent the pregression of liver or renal disease, or reduce the risk of developing hepatocellular carcinoma or neurologic abnormalities.o The medical treatment of choice is nits inone, formerly known as NTBC, which inhibits 4-OH phenylpyruvate dioxygenase (HPD), an early step in the tyrosine degradation pathway. This treatment reduces metabolic flow through the pathway and limits formation of the toxic compounds FAA and SA.Clinical manifestations of enzyme deficiencies in tyrosine catabolismDefective enzymeTyrosine aminotransferase4-hydroxy-phenylpyruvateHomogentisate dioxygenaseMaley1acetoacetate isomeraseFumarylacetoace-tate hydrolaseDisease name(s)Tyrosinemia type 11 Oculocutaneous tyrosinemia Richner-Hanhardt syndromeTyrosinemia type IIIAlkaptonuriaNo human patients describedTyrosinemia type I Hepatorenal tyrosinemiaElevated blood tyrosine+++++o?++Corneal ulcers++++/-o?oHyperkeratosis+++/-o?oMental retardation+/-+/-o?oArthritisoo+++?oLiver failureooo?+++Renal fanconi syndromeooo?++
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