What condition is associated with mental retardation, hypotonia, and cardiomegaly leading to death by age 2?

Pompe disease, also known as Glycogen storage disease type II, is an autosomal recessive disorder caused by a deficiency of the enzyme acid alpha-glucosidase. This enzyme is crucial for the breakdown of glycogen into glucose within lysosomes. When this enzyme is deficient, glycogen accumulates in various tissues, particularly affecting muscle tissue, heart, and the central nervous system.

The association with mental retardation, hypotonia, and cardiomegaly aligns with the clinical manifestations of Pompe disease, particularly in the infantile form. Infants typically present with severe hypotonia (floppiness), which stems from the weakness of the muscle due to the accumulation of glycogen. Cardiomegaly and heart failure can occur due to the deposition of glycogen in the cardiac muscle, leading to hypertrophic cardiomyopathy. Tragically, without treatment, many affected children do not survive past age 2 due to respiratory failure or heart failure.

In contrast, the other glycogen storage diseases listed do not typically present with the same combination of symptoms. McArdle's disease primarily affects skeletal muscle and usually does not present with hypotonia or cognitive impairment. Cori's disease features hypoglycemia and may have muscle weakness, but