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Topic Summary
This wiki is about Tay- Sachs Disease (TSD). It explains the diagnosis, treatment, prevention, and current research possible for the disease.

Learning Objectives

  • To obtain a basic understanding about the Tay-Sachs disease.
  • To understand the importance of diagnosis, prognosis, treatment, and prevention.
  • To understand the current research into different types of possible therapy treatment for the disease.

Descritption of the wiki

This wiki is about our class project in Genetic. After you read this site, you will gain understanding about Tay-Sachs disease, research and therapies.

What is Tay-Sachs Dissease (TSD)?

According to the National Institute of Neurological Disorders and Stroke (NINDS) "Tay-sachs disease (TSD) is a fatal genetic lipid storage disorder in which harmful quantities of a fatty substance called ganglioside GM2, build up in tissues and nerve cells in the brain." NINDS said that it is an autosomal recessive genetic disorder and a very rare disease because it strikes small children and babies. In the first few months of their life infants seen to be normal, but the symptoms appear when the nerve cells become swollen with the ganglioside GM2. Mental and physical abilities severly deteriorate. The signs, includes deafness, blindness, and difficulties in swallowing the food.
Tay-Sachs Disease is caused by a genetic mutation on the HEX A genome on chromosome 15 as researchers demonstrated in the late 20th century, from "News medical" web site.
http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm
http://www.news-medical.net/health/What-is-Tay-Sachs-Disease.aspx

History of Tay Sachs Disease

Dr. Warren Tay (1843-1927) was the first ophthalmologist who reported the symptoms of Tay-Sachs disease and he reported that cherry red spot in the eye is the sign of Tay-Sachs disease.
Dr. Bernard Sachs (1855-1944), a Neurologist from New York who reported the observance mostly babies in Eastern European Jewry.

http://www.ntsad.org/index.php/tay-sachs/history

Symptom

taysachsphoto1.jpg

cherry red spot in the eye is the sign of Tay-Sachs disease

The most severe form of Tay-Sachs Diseae begin to affect babies when they are only a few months old. Initially, they begin to loose their eye sights and react abnormally, and their development is delayed.
Image 1. http://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/Tay-sachsUMich.jpg/230px-Tay-sachsUMich.jpg

Healthy and Unhealthy Nerve Cells in Children with Tay-Sachs Disease

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Image 2: http://www.cleveland.com/taysachs/images/nerve1105.gif
http://www.cleveland.com/taysachs/wide/index.ssf?nerve1105.html

Image 3:

LysosomeTaySachs1.jpg

In This Image Tay Sachs Lysosomes Can't Digest Gangliodide GM2


Image 4:http://www.utm.utoronto.ca/~w3bio315/picts/lectures/lecture15/LysosomeTaySachs1.jpg

A video about Tay-Sachs disease

The Disease Appears In Three Forms

1.) Classic Infantile Tay Sachs Disease
This form is common for children who are older than 6 month. A child with a severe case my become blind.

2.)Juvenile Tay Sachs Disease
The symptom will show in children between 2 and 5 years of age due to the lackof Hexosaminidase-A (Hex-A) enzyme.

3.)Chronic Tay Sachs Disease/Late Onset Tay Sachs Disease
This is an unusual form of TSD. Children with this form are usually older, and they are totally lack the enzyme Hexosaminidase A (HEX- A).

http://en.wikipedia.org/wiki/Tay%E2%28%93Sachs_disease
http://www.news-medical.net/health/Tay-Sachs-Disease-Symptoms.aspx

Diagnosis And Detection

Preconception screening
Potential parents check for the possibility of carrying the mutation.
Antenatal screening
The fetus is checked for two copies of the HEX A mutation which have been inherited that will cause Tay-Sachs disease.

Carrier Testing
Potential couples consider the risk and possibility for having the disease.
Prenatal Testing
To determine if the fetus has been inherited the mutation from both parents.
This tests is use when both parents are uncertain whether they carry the disease. From the "News medical" website said that "prenatal testing can be performedby assay of HEX A enzyme activity in activity in fetal cells by chronic sampling or aminocentesis." (News Medical)

http://www.news-medical.net/health/Tay-Sachs-Disease-Diagnosis.aspx

Tay Sachs Disease Diagnosis
A blood test is common for testing the disease because it quickly determines the results.
The doctors uses the Ophthalmoscope to diagnose to detect red eye spot in patients. Microscopic analysis of neuron is also used to see if there is an additional build up of Ganglioside.

Tay-Sachs Disease Treatment
Anticonvulsant medicines are used to control the seizure.
Appropriate nutrition is necessary for the suffering children.

Tay Sachs Disease Prognosis
Tay Sachs Disease patients usually die at age 4 due to the infections.
The chances of longer survival are uncertain.
Few patients will live only until the age of 12 or 13 years old, but most will not live in adulthood.

Tay Sachs Disease Prevention
The prevention of the TSD can only be done by carrier testing and prenatal testing in order to check the existence of any copies of a mutated gene. Also, these tests are used for couples who are in a high-risk population such as Ashkenazi Jews.

Above progonosis, treatment,and prevention from
http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease

Genetic Factors

Tay-Sachs Disease is caused by a genetic defect in a single gene with one copy of that gene inherited from both parents. It is an autosomal recessive disease according to News Medical web site.
This mutation in the HEXA gene on chromosome 15 causes Tay-Sachs Disease.
The HEXA gene plays a critical role in the brain and spinal cord and provides instructions for making part of an enzyme, beta-hexosaminidase A. This enzyme is located in lysosomes. In cell lysosomes break down toxic substances and act as recycling centers. Within lysosomes, beta-hexosaminidase A helps break down a fatty substance called GM2 ganglioside.
As a result, the accumulation of this substance reaches to toxic levels, especially in the brain.
Because Tay-Sachs disease impairs the function of a lysosomal enzyme and involves the buildup of GM2 ganglioside, this condition is sometimes referred to as a lysosomal storage disorder or a GM2-gangliosidosis.

http://en.wikipedia.org/wiki/Tay%E2%80%93Sachs_disease
http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm

Image 5:

bb_feb2007_large.jpg

Image:http://www.sfn.org/siteobjects/published/0000BDF20016F63800FD712C3158BA55/0000BDF2000006250110C68C45857663/file/bb_feb2007_large.jpg

http://sites.google.com/site/geneticdisorders6/tay-saches

"In a healthy neuron, top, lysosomes act as the waste processing center of the cell. In Tay-Sachs disease, genetic deficiencies hobble lysosome enzymes that break down fatty cell products, also known as gangliosides, which build up and destroy the cell."(Morgan.M)

Image 6

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Chromosome 15 with Tays Sachs

http://www.google.com/imgres?q=tay+sachs&um=1&hl=en&sa=N&biw=1280&bih=822&tbm=isch&tbnid=9PIpIvsSo8eEBM:&imgrefurl=http://www.hinsdale86.org/staff/kgabric/Disease11/Tay%2520Sachs%2520Disease-Hexodaminidase%2520A/Conclusion.htm&docid=tkdDbos2O29EcM&imgurl=http://www.hinsdale86.org/staff/kgabric/Disease11/Tay%252520Sachs%252520Disease-Hexodaminidase%252520A/Conclusion_files/image001.gif&w=313&h=317&ei=ApapT4ztM-Hv0gGGhKS9BQ&zoom=1&iact=hc&vpx=281&vpy=470&dur=63&hovh=226&hovw=223&tx=91&ty=117&sig=100348008662220059075&page=1&tbnh=135&tbnw=127&start=0&ndsp=26&ved=1t:429,r:14,s:0,i:170

HOW A BABY BORN WITH TAY-SACHS DISEASE?
TSD is an inherited disease, so when both parents carry a Tay-Sachs gene, each parent transmits the defective gene to their child. A child who inherits two Tay-Sachs genes (one from each parent) produces no functional Hex-A enzyme and will get Tay-Sachs disease.

National Tay-Sachs & Allied Disease, association of Delaware Valley stated that when both parents are Tay-Sachs carriers, the probablity that their child will have the disease is 25% chance and there is 50% chance of having a child who will be a carrier. On the other hand, when only one parent is a carrier, there is no chance the child will have the disease. In addition the association of Delware Valley said that there is a 50% chance of having a child who will be a Tay-Sachs carrier.
The most severe form of Tay-Sachs disease begins to affect babies when they are only a few months old. Initially, their development is delayed. They begin to lose their vision and react abnormally. Gradually they become paralyzed. The symptoms of the disease are loss of hearing, seizures, inability to swallow food, and difficulties in breathing.
http://www.tay-sachs.org/taysachs_disease.php

220px-Autorecessive.svg.png

Autosomal Recessive Genetic Disorder.

Image 7:http://media.commercialappeal.com/mca/content/img/photos/2007/12/15/16eggs.jpeg]]

A BABY BORN WITH TAY-SACHS DISEASE
Image 8

16eggs.jpeg

http://media.commercialappeal.com/mca/content/img/photos/2007/12/15/16eggs.jpeg

Research and Therapies

Since there is yet unaffective treatment for this disease, the researchers are trying some potential therapies.

1. Enzyme Replacement Therapy (ERT)

2. Gene Therapy (GT)

3. Substrare Reductuon Therapy (SRT)

Video Of Gene Therapy

Powerpoint Presentation

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