Which of the following occurs in the lipidosis known as Tay-Sachs disease?
In the genetic disorder known as Tay-Sachs disease, ganglioside GM2 is not catabolized. As a consequence, the ganglioside concentration is elevated many times higher than normal. The functionally absent lysosomal enzyme is b-N- acetylhexosaminidase. The elevated GM2 results in irreversible brain damage to infants, who usually die before the age of 3 years. Under normal conditions, this enzyme cleaves N- acetylgalactosamine from the oligosaccharide chain of this complex sphingolipid, allowing fuher catabolism to occur. The cause of most lipidoses (lipid storage diseases) is similar. That is, a defect in catabolism of gangliosides causes abnormal accumulation. None of the other choices result in lipidotic disorders. Ref: Hopkin R., Grabowski G.A. (2012). Chapter 361. Lysosomal Storage Diseases. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.
Synthesis of a specific ganglioside is excessive
Xanthomas due to cholesterol deposition are observed
Phosphoglycerides accumulate in the brain
Ganglioside GM2 is not catabolized by lysosomal enzymes