Tay-Sachs disease symptoms appear quite early in childhood. Children who acquire it start to show symptoms at three to six months of age as the muscles used to turn over, crawl and sit are affected, making such actions difficult to impossible for the afflicted. Children with Tay-Sachs also startle in an exaggerated manner when confronted with loud noises. Tay-Sachs destroys the enzymes that work to clear growths in the brain and spinal cord, inhibiting children in physical and mental capacities.
Eventually, vision and hearing loss accompanies motor skills loss, seizures, paralysis and loss of intellectual abilities. Sufferers also may develop something called cherry-red spot in the back of the eye. As the disease advances, symptoms become worse and other organs are affected, eventually causing the child to die very early, usually before age 5. Disability in those who have Tay-Sachs symptoms usually become severe by age 2, with the child becoming completely disabled and unable to communicate or help itself.
There are also forms of the disease that can appear in adolescence and early adulthood but are usually milder than infant form and are extremely rare. These include loss of muscle coordination, weakness and movement and speech problems. The afflicted may also suffer from mental illness. The symptoms vary widely among individuals with the adolescent- and adult-onset form but usually start to manifest before age 5 and result in death by age 15. A form called late-onset Tay-Sachs may develop in which there is muscle weakness and slurred speech, but mental abilities remain normal.
Who is at risk?
Ashkenazi Jews, mostly from the Eastern and Central parts of Europe, are the most common sufferers of Tay-Sachs disease. This is believed to be because of a rare genetic mutation present in that population. Other groups that seem to acquire the disease mutations include French-Canadians from the province of Quebec, so-called Old Order Amish in the Pennsylvania region of the United States and the Cajun people of Louisiana. Tay-Sachs is a birth defect that can be detected with a blood test, so it is wise to have both parents tested as part of family planning.
Researchers believe that mutations in the HEXA gene are largely responsible for acquiring it. The HEXA gene is responsible for relaying details on creating an enzyme called beta-hexosaminidase A, which is largely found in the spinal cord and brain. As the enzyme decreases, GM2 gangliosides that the enzyme usually breaks down can build up. Eventually, the GM2 gangliosides begin to increase, destroying the brain and spinal cord neurons, resulting in full onset of the symptoms of Tay-Sachs disease.
How It Is Acquired
Children are believed to inherit the gene from both parents, but not everyone who carries the gene acquires the disease, so it is a serious issue to confront. If both parents are carriers of the gene that causes Tay-Sachs, there is a 50 percent chance that their offspring will carry the gene but be unaffected. There is a 25 percent chance they will not carry the gene, and a 25 percent chance that the child will get the disease. A genetic counselor can explain in detail the chances of acquisition after obtaining the results of the blood test and going over the family history.
Once pregnant, women can have the unborn child tested for the HEXA gene. If the tests detect HEXA, the child will have Tay-Sachs disease. If they do not detect HEXA, then the child will not have it. The tests can be administered as early as the 10th week of pregnancy, when a small sample of the placenta can be taken via an embryonic needle. This is called a chorionic villus sampling, or CVS.
Between the 15th and 18th week of pregnancy, doctors can administer an amniocentesis test for the Tay-Sachs gene. A sample of amniotic fluid is drawn from the womb and tested for the HEXA gene. At either point, the parents can decide to terminate the pregnancy if the tests unfortunately show Tay-Sachs disease is likely.
Tay-Sachs Is Rare
There is no current cure for Tay-Sachs, but fortunately, the odds of acquiring it are extremely rare; less than 20 cases per year are reported in the United States. Doctors identify patients with Tay-Sachs by a physical examination and blood test.
Although there is no cure, doctors and other medical professionals will work with the family to help alleviate pain, control seizures and help with muscle spasms that may occur. Family support is available from a number of charities, including the National Tay-Sachs and Allied Diseases Foundation and the March of Dimes Foundation.
While there is no cure for Tay-Sachs disease, research is ongoing, and with new breakthroughs in gene therapy or enzyme replacement, it is hoped that a way to arrest or eliminate the disease will arrive.
The National Tay-Sachs & Allied Diseases Association, a non-profit dedicated to supporting research in search of a cure, reports that gene therapy results in animals have been promising, and human clinical trials may be underway soon. The therapies explored either restore the missing enzyme or figh the waste that accumulates as a result of a lack of the enzyme. As of now, scientific researchers believe that no one cure will be found, but a combination of various techniques may stop the accumulated damage and perhaps reverse them.
There are clinical trials underway at the University of Minnesota and investigations by the Metachromatic Leukodystrophy Natural History Study and researchers participating in the Efficacy Study of an Online Educational Module before Carrier Genetic Screening in Persons of Ashkenazi Jewish Descent in Montreal, Canada. Admission to these studies is competitive, but some reimbursement for travel, lodging and living expenses may be available. Of course, as these are trials, there is no guarantee that the research will result in any reversal, halting or cure for the disease. Those remain hopes for the future.
Until such time as a cure or other arresting development is discovered, genetic counseling and testing is the best hope for avoiding the heartbreak associated with this terrible disease.