Tay-Sachs is a disease of the central nervous system; it is a neurodegenerative disorder. Tay-Sachs most commonly affects infants. In infants, it is a progressive disease that is unfortunately always fatal. Rarely, Tay-Sachs can occur in teens and adults, causing less severe symptoms.
A defective gene on chromosome 15 causes Tay-Sachs disease. This defective gene causes the body to not make a protein called hexosaminidase A. Without this protein, chemicals called gangliosides build up in nerve cells in the brain, destroying brain cells.
The disease is hereditary, which means it is passed down through families. An individual has to receive two copies of the defective gene—one from each parent—to become affected. If only one parent passes down the defective gene, the child becomes a carrier. He or she will not be affected, but may pass the disease down to his or her own children.
The disease is most common among Ashkenazi Jews. These are people whose families descend come from the Jewish communities Central or Eastern Europe. According to Dr. Michael Kaback, chief of Medical Genetics at U.C. San Diego, approximately one in 30 individuals in the American Ashkenazi Jewish population is a Tay-Sachs carrier. (Kaback, 1999)
There is no way to prevent the disease, but you can have genetic testing done to see if you are a carrier or if your fetus has the disease. If you or your spouse is a carrier, genetic testing can help you make a decision about whether or not to have children.
Symptoms of Infantile Tay-Sachs
Most affected infants have nerve damage starting in utero, with symptoms appearing at 12 weeks to 24 weeks gestation. Progression is quick and the child will typically pass away by four or five years old.
Symptoms of Tay-Sachs in infants include:
- decreased muscle tone
- increased startle response
- paralysis or loss of muscle function
- delayed mental and social development
- slow growth
- red spot on the macula (an oval-shaped area near the center of the retina in the eye)
If your child has a seizure or has trouble breathing, go to the emergency room or call 911 immediately.
Symptoms of Other Forms of Tay-Sachs
There are also late-onset juvenile, chronic, and adult forms of the disease, which are much more rare.
Individuals with the juvenile form of Tay-Sachs typically display symptoms between the ages of 2 and 10 and usually pass away by age 15.
Those with the chronic form of Tay-Sachs develop symptoms by the age of 10, but the disease progresses slowly. Symptoms may include slurred speech, muscle cramps, and tremors. Life expectancy varies with this form of the disease, and some individuals have a normal lifespan.
Adult Tay-Sachs is the mildest form. Symptoms appear during adolescence or adulthood. Affected individuals usually have muscle weakness, slurred speech, an unsteady gait, memory problems, and tremors. The severity of symptoms and life expectancy varies.
Prenatal tests, such as chorionic villus sampling (CVS) and amniocentesis, can diagnose Tay-Sachs disease. Genetic testing is generally done when one or both members of a couple are carriers of the disease.
CVS is performed between 10 and 12 weeks of pregnancy and involves taking a sample of cells from the placenta via the vagina or abdomen. Amniocentesis is done between 15 and 20 weeks of pregnancy and involves extracting a sample of the fluid surrounding the fetus using a needle through the abdomen.
If a child is displaying symptoms of Tay-Sachs, a doctor can perform a physical examination and collect a family history. Enzyme analysis can be done on the child’s blood or tissue samples, and an eye exam may reveal a red spot on his or her macula.
There is no cure for Tay-Sachs. Treatment typically consists of keeping the patient comfortable. This is called “palliative care.” Palliative care may include medication for pain or to control seizures, physical therapy, feeding tubes, and respiratory care to reduce mucus buildup in the lungs.
Emotional support for the family is also important. Seeking out support groups can help you cope. Taking care of a sick child is emotionally challenging and talking with other families combating the same disease can be comforting.