Tay-SachsDrew Sivertsen

History

Tay-Sachs is named after two physicians Warren Tay – was an ophthalmologist who

was the first to discover a red dot on the retina of one of his patients in 1881. This red “cherry spot” is a telltale sign of TSD

Bernard Sachs- was a neurologist who studied and was able to determine the changes that took place inside the cells of Tay-Sachs Disease. He also recognized that was an inherited condition that ran in families ( European (Ashkenazi) Jewish )

Diagnosis

All Tay-Sachs patients will have a red dot or “macula” (oval shaped) on the back of their retina

This area is red due to the gangliosides in the surrounding retinal ganglion cells (ganglion cells are neurons in the central nervous system

They receive visual instructions from the photorecetptors

Without molecular experiments, the red dot is the only deifinitive diagnosis of TSD

How it occurs Tay-Sachs is a genetic

mutation on the HEXA gene on the chromosome 15 (between 23 and 24)

The HEXA gene’s job is to provide instructions for making one part of the enzyme beta-hexosaminidase A

Beta-hexosaminidase A holds a key function in the central nervous system (spinal cord and brain)

How it occurs cont’d With this mutation, the beta-

hexosaminidase A enzyme is unable to break down a fatty lipid called gangliosideGm2

The enzyme’s difficulty in breaking it down results in the toxic build up of gangliosideGm2

It then begins to rapidly destroy brain cells during the early growth of a child

The brain is not able to develop correctly due to the lack of Hexosaminidase A and its ability to function properly

Tay-Sachs is an autosomal recessive disorder. This means that there must be two copies of the gene in order for the disease to develop. If both parents are carriers of Tay-Sachs, there is a 25% chance their child will be infected with the disease. The disease can be passed to future generations

Phenotypic effects

Babies will appear to be developing normally until about 6 months

Loss of peripheral vision is an early symptom At about the age of 2, a child may have

recurrent seizures and a slowing down of their mental capacity

A child with TSD may also experience deafness, blindness, retardation, paralysis and ultimately death

Treatments

As of now, there is no known treatment or cure for Tay-Sachs

There have been break throughs in the exploration of “enzyme replacement therapy”

This could potentially provide the baby with the HEXA that is absent

Another is gene therapy, transfer of a normal gene to replace the abnormal gene

Bibliography

"Tay-Sachs." National Institute of Neurological Disorders and Stroke. N.p., n.d. Web. 26 Mar. 2010.<http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm>.

Genetics Home Reasearch. N.p., n.d. Web. 26 Mar. 2010.<http://ghr.nlm.nih.gov/condition=taysachsdisease>.

Kids Health: Tay-Sachs. N.p., n.d. Web. 26 Mar. 2010. <http://kidshealth.org/parent/medical/genetic/tay_sachs.html>.