Tay-Sachs+disease

= = toc = = =Tay-Sachs = by: Adrienne Harper

Background information
[|Tay-Sachs Disease(TSD)] is inherited in an autosomal recessive pattern. The disease occurs when harmful quantities of a fatty acid derivative called a [|ganglioside] accumulate in the nerve cells of the brain. The disease was named after British ophtalmologist Warren Tay who described the red spot on the retina of the eye in 1881. And it was also named after American neurologist Bernard Sachs, who described the cellular changes of Tay-Sachs and noted an increased affect on Eastern Europe Jewish population

How is Tay-Sachs disease inherited?
Tay-Sachs disease affects children who inherit two copies of an altered gene from their carrier parents. Carriers of Tay-Sachs disease are not affected themselves, because they have a working gene as well as an altered one. Carrier parents have a one-in-four chance of having an affected child, a one-in-two chance of having a child who is an unaffected carrier and a one-in-four chance of having a child who doesn't carry any altered genes.

What causes Tay-Sachs?
Tay-Sachs disease is caused by a genetic mutation on the HEXA gene on chromsome 15. These mutations are common among Ashkenazi Jews. Most HEXA mutations are rare and they do not occur in genetically isolated populations.

What are the symptoms?
Tay-Sachs is classified by the time of the onset neurological symptoms. All patients with the disease have a red spot, which is easily observable by a doctor using an opthalmoscope, in the back of the eyes. The three groups are:


 * Infatile TSD
 * Juvenile TSD
 * Adult/ Late onset TSD

//**Infatile TSD**//: Infants with Tay-Sachs disease appear to develop at a normal pace for the first 6 months of their lives. The as the nerve cells become infected with gangliosides, a restless deterioration of mental and physical abilities occur. The child becomes blind, deaf, and loses the ability to swallow. The muscles start to weaken and lose their functions and paralysis occurs. Death usually occurs before the age of 4-5

//**Juvenile TSD**//: This is extremely rare,it usually presents its self in children between 2 and 10 years old. They develop speech and motor difficulties, trouble swallowing, and other complications that usually cause them to die anywhere from age 5 up to age 15. //**Adult/Late onset TSD:**// This form is also rare, it occurs in adults in their early 20's to their late 30's. Many are mis diagnosed and it could start developing as early as their adolescent years. They have difficulty speaking and swallowing, and their mobility is affected so much that many are bound to a wheelchair. They also have psychiatric symtoms particularily schizophrenic-like psychosis but most live full adult lives with medications for the seizsures.



**Is there any treatment?**
Presently there is no treatment for Tay-Sachs disease. Anticonvulsant medicine may initially control seizures. Other supportive treatment includes proper nutrition and hydration and techniques to keep the airway open. Children may eventually need a feeding tube. As for adults they usually can lead normal lives wiht assistance from a wheel chair and medication.

Mutations
The disease is caused from mutations on chromosome 15 in the HEXA gene. These mutations included base pair insertions and deletions, splice site mutations, point mutations, and other more complex patterns. For example, a 4 base pair in exon 11 results in an altered reading frame from the HEXA gene. This mutation leads to the infatile form of Tay-Sachs disease.



http://en.wikipedia.org/wiki/Tay_Sachs http://www.sciencemuseum.org.uk/on-line/genes/232.asp www.aps.anl.gov content.answers.com/.../wp/en/f/fd/Tay-Sachs.jpg
 * Work Cited**