Type II glycogen storage disorder is due to deficiency of:
**Core Concept**
Type II glycogen storage disorder, also known as Pompe disease, is a genetic disorder caused by the deficiency of an enzyme responsible for breaking down glycogen to glucose in the lysosomes. This enzyme is crucial for glycogen metabolism in various tissues, including muscles and the liver.
**Why the Correct Answer is Right**
The correct enzyme responsible for breaking down glycogen to glucose in the lysosomes is acid alpha-glucosidase (also known as acid maltase). This enzyme catalyzes the hydrolysis of alpha-1,4-glycosidic bonds in glycogen, releasing glucose molecules that can then be further metabolized. Deficiency of acid alpha-glucosidase leads to the accumulation of glycogen in lysosomes, causing cellular damage and the symptoms associated with Pompe disease.
**Why Each Wrong Option is Incorrect**
**Option A:** Debranching enzyme is involved in the breakdown of glycogen, but it is not the primary enzyme deficient in Type II glycogen storage disorder. The debranching enzyme is responsible for removing branch points in glycogen, but it is not the key enzyme in Pompe disease.
**Option B:** Phosphorylase enzyme is involved in glycogenolysis, but it is not the enzyme deficient in Type II glycogen storage disorder. Phosphorylase is responsible for breaking down glycogen to glucose-1-phosphate, but it is not the primary enzyme affected in Pompe disease.
**Option C:** Glycogen synthase is involved in glycogen synthesis, but it is not the enzyme deficient in Type II glycogen storage disorder. Glycogen synthase is responsible for adding glucose molecules to the growing glycogen chain, but it is not the key enzyme in Pompe disease.
**Clinical Pearl / High-Yield Fact**
Pompe disease is an autosomal recessive disorder, meaning that both parents must be carriers of the mutated gene to pass it on to their offspring. This is an important clinical correlation for genetic counseling and family planning.
**Correct Answer:** A. Acid alpha-glucosidase (also known as acid maltase).