Why is glycogenolysis impaired in von Gierke disease?

Von Gierke disease (also known as Glycogen Storage Disease Type I) is caused by a deficiency in the enzyme glucose-6-phosphatase. This enzyme is essential for the final step of glycogenolysis and gluconeogenesis, where glucose-6-phosphate (G6P) is converted into free glucose. In the absence of glucose-6-phosphatase, the breakdown of glycogen in the liver is impaired because glucose-6-phosphate cannot be converted into glucose for release into the bloodstream. As a result, individuals with von Gierke disease experience hypoglycemia (low blood sugar) during periods of fasting or between meals, as they cannot release glucose from their glycogen stores. This leads to abnormal accumulation of glycogen in the liver and kidneys.