A 3-year-old girl presents with progressive muscle weakness, a cherry-red spot on fundoscopy, hepatosplenomegaly, and neurodegeneration. Enzyme assay shows absent hexosaminidase A activity. The storage material accumulating is:
- A GM2 ganglioside ✓
- B Glucocerebroside
- C Sphingomyelin
- D Galactocerebroside
Correct answer: A. GM2 ganglioside
Explanation
Tay-Sachs disease results from deficiency of hexosaminidase A (alpha subunit mutation), which cleaves the terminal N-acetylgalactosamine from GM2 ganglioside. GM2 accumulates in neurons causing progressive neurodegeneration. Glucocerebroside accumulates in Gaucher disease (glucocerebrosidase deficiency); sphingomyelin in Niemann-Pick disease (sphingomyelinase deficiency); galactocerebroside in Krabbe disease (galactocerebrosidase deficiency).
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.