Hyperuricemia is caused in newborn due to defect in:
**Core Concept**
Hyperuricemia in newborns is often due to a defect in purine metabolism, specifically the inability to break down hypoxanthine and xanthine to uric acid. This defect can lead to an accumulation of these purine metabolites, resulting in hyperuricemia.
**Why the Correct Answer is Right**
The correct answer is related to the enzyme xanthine dehydrogenase (XDH), which is crucial in converting hypoxanthine and xanthine to uric acid. In newborns, a deficiency of this enzyme leads to an inability to metabolize these purine metabolites, resulting in their accumulation and subsequent hyperuricemia. This condition is known as xanthinuria.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the metabolism of purine metabolites and is therefore incorrect.
**Option B:** While defects in other enzymes can lead to hyperuricemia, they are not the primary cause in newborns.
**Option C:** This option is not directly related to the metabolism of purine metabolites and is therefore incorrect.
**Clinical Pearl / High-Yield Fact**
Xanthinuria is a rare genetic disorder characterized by the inability to break down hypoxanthine and xanthine due to a deficiency of xanthine dehydrogenase. It is essential to diagnose and manage this condition early to prevent kidney damage and other complications.
**Correct Answer:** C.