Sandhoff’s disease is due to absence of which enzyme?
**Core Concept**
Sandhoff's disease is a rare, autosomal recessive lysosomal storage disorder characterized by the accumulation of gangliosides and other glycosphingolipids within neurons, leading to progressive neurological deterioration.
**Why the Correct Answer is Right**
The enzyme responsible for breaking down these lipids is hexosaminidase B. In Sandhoff's disease, there is a deficiency of this enzyme, resulting in the accumulation of GM2 ganglioside within neurons. This accumulation causes cellular dysfunction and ultimately leads to neuronal death. The deficiency of hexosaminidase B is due to mutations in the HEXB gene.
**Why Each Wrong Option is Incorrect**
**Option A:** The correct enzyme associated with Tay-Sachs disease, not Sandhoff's disease. Tay-Sachs disease is caused by a deficiency of hexosaminidase A.
**Option B:** This enzyme is involved in the breakdown of sphingomyelin, which is associated with Niemann-Pick disease, not Sandhoff's disease.
**Option C:** This enzyme is involved in the breakdown of glucocerebroside, which is associated with Gaucher's disease, not Sandhoff's disease.
**Clinical Pearl / High-Yield Fact**
Sandhoff's disease is often confused with Tay-Sachs disease, but the key difference lies in the enzyme deficiency: hexosaminidase A in Tay-Sachs and hexosaminidase B in Sandhoff's.
**Correct Answer:** B. Hexosaminidase B.