Enzyme deficient in tyrosinemia type 1 ?
**Core Concept**
Tyrosinemia type 1 is a rare genetic disorder caused by a deficiency in an enzyme responsible for breaking down an amino acid called tyrosine. This leads to the accumulation of toxic byproducts, resulting in severe liver and kidney damage.
**Why the Correct Answer is Right**
The correct answer is fumarylacetoacetate hydrolase (FAH). FAH is the enzyme that catalyzes the final step in the breakdown of tyrosine. Without functional FAH, tyrosine and its byproducts accumulate, causing cellular damage. The deficiency of FAH leads to the characteristic symptoms of tyrosinemia type 1, including liver and kidney dysfunction.
**Why Each Wrong Option is Incorrect**
* **Option A:** Phenylalanine hydroxylase is the enzyme deficient in phenylketonuria (PKU), a different genetic disorder.
* **Option B:** Homogentisate 1,2-dioxygenase is the enzyme deficient in alkaptonuria, another genetic disorder that affects the breakdown of tyrosine but is distinct from tyrosinemia type 1.
* **Option C:** Tyrosine aminotransferase is involved in the breakdown of tyrosine, but it is not the enzyme deficient in tyrosinemia type 1.
**Clinical Pearl / High-Yield Fact**
Tyrosinemia type 1 is a serious condition that requires early diagnosis and treatment to prevent liver and kidney failure. Patients often require a strict diet low in tyrosine and phenylalanine, as well as medications to manage the condition.
**Correct Answer:** C. Fumarylacetoacetate hydrolase (FAH).