<s>[INST] context: Glycogen storage disease type II, also called Pompe disease, is an autosomal recessive metabolic disorder which damages muscle and nerve cells throughout the body. It is caused by an accumulation of glycogen in the lysosome due to deficiency of the lysosomal acid alpha-glucosidase enzyme. It is the only glycogen storage disease with a defect in lysosomal metabolism, and the first glycogen storage disease to be identified,The disease is caused by a mutation in a gene (acid alpha-glucosidase: also known as acid maltase) on long arm of chromosome 17.Most cases appear to be due to three mutations. A transversion (T - G) mutation is the most common among adults with this disorder. This mutation interrupts a site of RNA splicing.The gene encodes a protein--acid alpha-glucosidase (EC 3.2.1.20)--which is a lysosomal hydrolase. The protein is an enzyme that normally degrades the alpha -1,4 and alpha -1,6 linkages in glycogen, maltose and isomaltose and is required for the degradation of 1-3% of cellular glycogen. The deficiency of this enzyme results in the accumulation of structurally normal glycogen in lysosomes and cytoplasm in affected individuals.clinical features: Accumulation of glycogen in lysosomes: Juvenile onset variant, muscle hypotonia, death from hea failure by age 2; adult onset variant, muscle dystrophy [/INST] question: Glycogen storage disorder is- | options: A: Niemann - Pick disease B: Gaucher disease C: Tay- Sacks disease D: Pompe's disease | answer: D </s>