Tyrosinemia type I results from deficiency of which enzyme?

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Multiple Choice

Tyrosinemia type I results from deficiency of which enzyme?

Tyrosinemia type I is caused by a deficiency in fumarylacetoacetate hydrolase, the enzyme that catalyzes the final step of tyrosine breakdown to fumarate and acetoacetate. When this step is blocked, toxic intermediates build up in the liver and kidneys, leading to serious hepatic and renal dysfunction and other complications. This specific enzyme deficiency distinguishes type I from other tyrosinemias caused by defects earlier in the pathway, such as tyrosine aminotransferase (type II) or phenylalanine hydroxylase (PKU), or homogentisic acid oxidase (alkaptonuria). Treatments target the toxic upstream buildup, for example with NTBC to inhibit upstream steps and with dietary restrictions of phenylalanine and tyrosine.

Tyrosinemia type I is caused by a deficiency in fumarylacetoacetate hydrolase, the enzyme that catalyzes the final step of tyrosine breakdown to fumarate and acetoacetate. When this step is blocked, toxic intermediates build up in the liver and kidneys, leading to serious hepatic and renal dysfunction and other complications. This specific enzyme deficiency distinguishes type I from other tyrosinemias caused by defects earlier in the pathway, such as tyrosine aminotransferase (type II) or phenylalanine hydroxylase (PKU), or homogentisic acid oxidase (alkaptonuria). Treatments target the toxic upstream buildup, for example with NTBC to inhibit upstream steps and with dietary restrictions of phenylalanine and tyrosine.

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