Question

Sphingomyelinase deficiency is seen in:

• A. Niemann-Pick disease
• B. Farber's disease
• C. Tay-Sachs disease
• D. Krabbe's disease

Hint:

Sphingomyelin builds up, so think of the disease named for that lipid.

Answer 1

The Correct Option is A

Step 1: These are all sphingolipidoses, a group of lysosomal storage disorders. Each is defined by a specific missing enzyme and the substrate that then accumulates.
Step 2: Sphingomyelinase (acid sphingomyelinase) normally breaks down sphingomyelin into ceramide and phosphocholine. Its deficiency means sphingomyelin builds up. This is Niemann-Pick disease (types A and B), which presents with hepatosplenomegaly and, in type A, neurodegeneration and a cherry-red macular spot.
Step 3: The other options use different enzymes: Farber disease is ceramidase deficiency (ceramide accumulates); Tay-Sachs disease is hexosaminidase A deficiency (GM2 ganglioside accumulates); Krabbe disease is galactocerebrosidase (beta-galactocerebrosidase) deficiency (galactocerebroside accumulates).
Step 4: So sphingomyelinase deficiency maps to Niemann-Pick disease.
Answer: Option A (Niemann-Pick disease).