**Question:** A genetic disorder renders fructose 1,6 bisphosphatase in liver less sensitive to regulation by fructose 2,6- bisphosphate. All of the following metabolic changes occur EXCEPT:

A. Increased glucose production
B. Decreased ammonia production
C. Altered uric acid production
D. Impaired gluconeogenesis

**Correct Answer:** D. Impaired gluconeogenesis

**Core Concept:** Fructose 1,6 bisphosphatase (FBPase) is an essential enzyme involved in the regulation of glucose production in the liver. It plays a crucial role in the process of gluconeogenesis, a critical pathway for producing glucose from non-carbohydrate sources when glucose levels are low. Fructose 2,6-bisphosphate (F2,6BP) is a key allosteric regulator of FBPase, increasing its activity to enhance gluconeogenesis.

**Why the Correct Answer is Right:** In the context of the genetic disorder mentioned, FBPase becomes less sensitive to the regulation by F2,6BP. As a result, the enzyme's activity is not enhanced as it should be, leading to reduced gluconeogenesis. This leads to impaired glucose production within the liver, which is essential for maintaining blood glucose levels and overall body glucose homeostasis.

**Why Each Wrong Option is Incorrect:**

A. Increased glucose production: The genetic disorder causing FBPase to be less sensitive to F2,6BP would likely result in decreased glucose production, not increased.

B. Decreased ammonia production: Ammonia is primarily cleared from the blood by the liver via ureagenesis, a process unrelated to FBPase regulation and gluconeogenesis. Thus, this option is incorrect.

C. Altered uric acid production: Uric acid production is regulated by xanthine oxidase, not FBPase or gluconeogenesis. Therefore, this option is irrelevant to the question.

**Clinical Pearl:** Fructose 1,6 bisphosphatase regulation by F2,6BP is essential for maintaining glucose homeostasis and preventing hypoglycemia. Lack of this regulation can lead to life-threatening hypoglycemia in infants due to the child's inability to produce glucose when needed. This highlights the importance of understanding the regulation of gluconeogenesis and its role in glucose production.