Tay-Sachs disease vs Niemann-Pick disease and Krabbe disease
How to tell Tay-Sachs disease and Niemann-Pick disease and Krabbe disease apart when a board question makes them look alike.
Tay-Sachs is GM2 with no hepatosplenomegaly; Niemann-Pick is foam cells with hepatosplenomegaly; Krabbe is demyelinating globoid-cell disease.
Side by side
Tay-Sachs causes progressive neurodegeneration, exaggerated startle, developmental regression, cherry-red macula, and no hepatosplenomegaly from hexosaminidase A deficiency.
Niemann-Pick causes neurodegeneration with hepatosplenomegaly and foam cells; Krabbe causes CNS plus peripheral demyelination with globoid cells and psychosine accumulation.
Hexosaminidase A deficiency blocks GM2 ganglioside degradation inside lysosomes.
Sphingomyelinase/NPC defects disrupt sphingomyelin/cholesterol handling, while galactocerebrosidase deficiency injures myelin through psychosine accumulation.
Cherry-red macula plus absent hepatosplenomegaly and GM2 accumulation supports Tay-Sachs.
Foam cells and hepatosplenomegaly support Niemann-Pick; globoid cells and peripheral demyelination support Krabbe.
The trap
All can cause neurodegeneration, so organomegaly, foam cells, globoid cells, and substrate separate them.
The repair move
For infant neurodegeneration with cherry-red macula, check hepatosplenomegaly before naming Tay-Sachs.
Try a free question
CoreA 10-month-old infant of Ashkenazi Jewish descent has lost head control, has an exaggerated startle to clapping (hyperacusis), and shows a cherry-red macula on funduscopy. Liver and spleen are not palpable. Which enzyme deficiency is most likely?
Show answer and explanation
Answer: A. Hexosaminidase A (Tay-Sachs disease). Tay-Sachs disease is hexosaminidase A deficiency; GM2 ganglioside accumulates in neurons producing progressive neurodegeneration, hyperacusis, and cherry-red macula. The ABSENCE of hepatosplenomegaly is the key separator from Niemann-Pick.
Why the other choices are tempting
- B. Sphingomyelinase deficiency (Niemann-Pick A) presents with hepatosplenomegaly plus neurodegeneration, not isolated neurologic disease.
- C. Galactocerebrosidase deficiency (Krabbe) causes peripheral demyelination with globoid cells, not isolated cherry-red macula.
- D. Glucocerebrosidase deficiency (Gaucher) causes bone crises and hepatosplenomegaly with Gaucher cells.
- E. Alpha-galactosidase A deficiency (Fabry) presents in adolescents/adults with angiokeratomas and neuropathy.
Flashcards
Tap a card to flip it.
What clue supports Tay-Sachs disease?
Choose Tay-Sachs disease when the stem gives this pattern: Tay-Sachs causes progressive neurodegeneration, exaggerated startle, developmental regression, cherry-red macula, and no hepatosplenomegaly from hexosaminidase A deficiency.
What clue supports Niemann-Pick disease and Krabbe disease?
Choose Niemann-Pick disease and Krabbe disease when the stem gives this contrasting pattern: Niemann-Pick causes neurodegeneration with hepatosplenomegaly and foam cells; Krabbe causes optic atrophy, peripheral neuropathy, globoid cells, and psychosine accumulation.
Quick answers
What is the fastest way to tell Tay-Sachs disease from Niemann-Pick disease and Krabbe disease?
Tay-Sachs is GM2 with no hepatosplenomegaly; Niemann-Pick is foam cells with hepatosplenomegaly; Krabbe is demyelinating globoid-cell disease.
What is the key clue for Tay-Sachs disease?
Tay-Sachs causes progressive neurodegeneration, exaggerated startle, developmental regression, cherry-red macula, and no hepatosplenomegaly from hexosaminidase A deficiency.
What is the key clue for Niemann-Pick disease and Krabbe disease?
Niemann-Pick causes neurodegeneration with hepatosplenomegaly and foam cells; Krabbe causes CNS plus peripheral demyelination with globoid cells and psychosine accumulation.
What is the common trap with Tay-Sachs disease vs Niemann-Pick disease and Krabbe disease?
All can cause neurodegeneration, so organomegaly, foam cells, globoid cells, and substrate separate them.