Tay Sach disease (PowerPoint presentation)

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  • Tay–Sachs disease (also known as GM2 gangliosidosis or hexosaminidase A deficiency) is an autosomal recessive genetic disorder.
  • occurs when harmful quantities of cell membrane components known as gangliosides accumulate in the brain's nerve cells, eventually leading to the premature death of the cells
  • Tay–Sachs disease a member of the sphingolipidoses
  • There is no known cure or treatment. 


Signs and symptoms
classified into several forms, based on the onset age of neurological symptoms.


1. Infantile Tay–Sachs disease.
  • develop normally for the first six months after birth.
  • The child becomes blind, deaf, unable to swallow, atrophied, and paralytic. 
  • Death usually occurs before the age of four
2. Juvenile Tay–Sachs disease. 
  • rarer 
  • initially seen in children between two and ten years old. 
  • develop cognitive and motor skill deterioration, dysarthria, dysphagia, ataxia, and spasticity. 
  • die between five and fifteen years old.
3. Adult/Late-Onset Tay–Sachs disease. 
  • first symptoms during the 30s or 40s. 
  • usually not fatal as the effects can stop progressing. 
  • characterized by unsteadiness of gait and progressive neurological deterioration. 
  • begin to be seen in adolescence or early adulthood – include speech and swallowing difficulties, unsteadiness of gait, spasticity, cognitive decline, and psychiatric illness, particularly a schizophrenia-like psychosis.
  • become full-time wheelchair users in adulthood. 
Pathophysiology 


  • insufficient activity of the enzyme hexosaminidase A
  • Hexosaminidase A is a vital hydrolytic enzyme, found in the lysosomes, that breaks down phospholipids. When hexosaminidase A is no longer functioning properly, the lipids accumulate in the brain.
  • Hexosaminidase A specifically breaks down fatty acid derivatives called gangliosides
  • The hydrolysis of GM2-ganglioside requires three proteins. 
  • Two of them are subunits of hexosaminidase A; 
  • the third is a small glycolipid transport protein, the GM2 activator protein (GM2A), which acts as a substrate-specific cofactor for the enzyme. Deficiency in any one of these proteins leads to ganglioside storage, primarily in the lysosomes of neurons. 
Diagnosis

  • measure the activity of hexosaminidase (decrease in activity as is its percentage) in serum, fibroblasts or leukocytes. 
  • confirmation by molecular analysis can be pursued.
  • have a "cherry red" macula in the retina

  • This red spot is a retinal area that appears red because of gangliosides in the surrounding retinal ganglion cells. The choroidal circulation is showing through "red" in this foveal region where all retinal ganglion cells are pushed aside to increase visual acuity. Thus, this cherry-red spot is the only normal part of the retina.
  • Microscopic analysis of the retinal neurons shows they are distended from excess ganglioside storage.

  • Unlike other lysosomal storage diseases (e.g., Gaucher disease, Niemann–Pick disease, and Sandhoff disease), hepatosplenomegaly (liver and spleen enlargement) is not seen in Tay–Sachs.


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