Tay-Sachs Disease vs Niemann-Pick Disease: Lysosomal Storage Diseases

Tay-Sachs disease is an autosomal recessive disorder characterized by mental retardation, blindness, muscular weakness, lysosomes with onion skin, and the appearance of a cherry red spot on the macula. The enzyme deficient in Tay-Sachs disease is Hexosaminidase A. Hexosaminidase A is an enzyme that catalyzes GM2 ganglioside into GM3 ganglioside, and because hexosaminidase A enzyme is deficient in Tay-Sachs disease, GM2 gangliosides accumulate in the brain. Tay-Sachs disease is common in Ashkenazi Jewish patient populations.

Niemann-Pick disease is an autosomal recessive disorder characterized by progressive neurodegeneration, hepatosplenomegaly, foam cells, and cherry red spot on the macula. The enzyme deficient in Neimann-Pick disease is Spingomyelinase. Spingomyelinase is an enzyme that catalyzes the reaction to convert sphingomyelin into ceramide. Because spingomyelinase is deficient, spingomyelin accumulates.

Differences between Tay-Sachs Disease and Niemann-Pick Disease

1. Unlike patients with Niemann-Pick disease, Tay-Sachs disease patients do not have hepatosplenomegaly, or large liver.

2. Compared to Tay-Sachs disease, a defining symptom of Niemann-Pick disease is that patients with Niemann-Pick disease have foam cells or lipid-laden macrophages.

Histology: Tay-Sachs vs Niemann Pick Disease

3. The histology for diagnosing Tay-Sachs disease and Niemann-Pick disease also differs. Niemann-Pick disease’s histological diagnosis is most notable for its lipid laden macrophages. In other words, under the microscope and histology slides, doctors can see a patient’s macrophage with an unusual large amount of lipids inside them, known as foam cells. Unlike Niemann-Pick disease, Tay-Sachs disease is notable for its lysosomes with onion skin for histology – literally, the lysosomes in the cells look like onions with multiple circular peel layers in it!

4. Tay-Sachs disease is unique and common in patients with Ashkenazi Jewish descent.

Summary of Differences: Tay-Sachs Disease vs Niemann-Pick Disease

USMLE Lysosomal Storage Diseases: Easy Table Chart on Tay-Sachs disease and Niemann-Pick Disease

Similarities between Tay-Sachs Disease and Niemann-Pick Disease

1. Both Tay-Sachs Disease and Niemann-Pick Disease are lysosomal storage diseases, meaning there is an abnormal metabolic product because of a deficiency in one of the many lysosomal enzymes that would normally break down lipids.

2. Both Tay-Sachs Disease and Niemann-Pick DIsease patients have cherry-red spots on their maculas, as a symptom. Patients also both have progressive neurodegneration.

3. Another similarity is that the inheritance for both Tay-Sachs disease and Niemann-Pick disease is autosomal recessive.

Summary of Similarities: Tay-Sachs Disease and Niemann-Pick Disease

Works Cited

First Aid USMLE Step 1 2019. Tao Le, Vikas Bhushan, Matthew Socha , Yash Chavda, et al.

Niemann Pick Disease – Genetics. https://ghr.nlm.nih.gov/condition/niemann-pick-disease

Tay-Sachs Disease – NIH. https://rarediseases.info.nih.gov/diseases/7737/tay-sachs-disease

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