Biology

Tay-Sachs Disease vs Niemann-Pick Disease: Similarities and Differences

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.

Cherry red spot on macula for both Tay-Sachs and Niemann Pick Disease patients; A similarity between Tay-Sachs Disease and Niemann-Pick Disease
What is the genetic inheritance of Tay-Sachs disease and Niemann-Pick disease? (Easy)
Both are autosomal recessive.
Both are X-linked recessive.
Both are autosomal dominant.
Tay-Sachs: autosomal recessive; Niemann-Pick: autosomal dominant
Niemann-Pick: autosomal recessive; Tay-Sachs: autosomal dominant
Niemann-Pick: X-linked recessive; Tay-Sachs: autosomal recessive
Niemann-Pick: X-linked recessive; Tay-Sachs: autosomal dominant

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.

Foam cell histology for Niemann Pick Disease; Different from Tay-Sachs Disease; Source: Wikimedia Commons

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

Tay-Sachs DiseaseNiemann-Pick Disease
Symptom: No enlarged liverSymptom: Yes, enlarged liver
Histology: No foam cellsHistology: Yes, foam cells and lipid-laden macrophages
Histology: Yes, lysosomes with onion skinHistology: No lysosomes with onion skin
Enzyme: GangliosidaseEnzyme: Sphingomyelinase
Accumulated Substrate: GM2 GangliosideAccumulated Substrate: Sphingomyelin
Deficient Product: GM3Deficient Product: Ceramide
Copyright 2019 Moosmosis
A 3-year-old boy from the local orphanage presents to the clinic with his caretaker for worsening vision and severely delayed childhood milestones. On physical exam, he was found to have a cherry red spot on the macula, and an enlarged palpable liver. There is no information regarding his parents’ medical history. What enzyme is likely impacted in this patient? [part 1 question]
Sphingomyelinase
Ceramidase
Gangliosidase
alpha-Galactosidase
Glucocerebrosidase
Arylsulfatase

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

A 3-year-old boy from the local orphanage presents to the clinic with his caretaker for worsening vision and severely delayed childhood milestones. On physical exam, he was found to have a cherry red spot on the macula, and an enlarged palpable liver. There is no information regarding his parents’ medical history. What substrate would be accumulated in this patient? [part 2]
Sphingomyelin
Ceramide
GM3
GM2 Ganglioside

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.

Autosomal recessive inheritance for Tay-Sachs Diseae and Niemann-Pick disease; Similarity of Tay-Sachs and Niemann-Pick
From the same orphange as the previous 3-year-old-boy, a 2-year-old girl is brought to the clinic presenting with similar symptoms of delayed milestones, cherry red macula, but no enlarged liver. What product would be deficient in her disease?
GM3
GM2
Ceramide
Sphingomyelin
GM2 Ganglioside

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

Similarities between Tay-Sachs and Niemann-Pick Disease: USMLE Lysosomal Storage Diseases
Symptom: Cherry-red spot on macula eye
Symptom: Neuronal degeneration
Inheritance: Autosomal Recessive AR
Copyright 2019 Moosmosis
The two-year-old girl from the orphanage was diagnosed with an inheritable lysosomal disease. What was her probability of being affected by this disease if both her parents were healthy and unaffected?
25% chance
0% chance
100% chance
50% chance
75% chance

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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