What Is It?
Tay-Sachs disease is an inherited disease caused by an abnormal gene. People with this abnormal gene do not have an important enzyme called hexosaminidase A (HEXA) that helps to break down a fatty material called ganglioside GM2. This material builds up in the brain, and eventually damages nerve cells and causes neurological problems.
Infants usually begin to show signs of the disease between 3 months and 6 months of age. Children with Tay-Sachs disease can become deaf, blind and paralyzed, and usually die by the age of 5.
Tay-Sachs disease is an autosomal recessive inherited disorder, meaning a child inherits one copy of the abnormal gene from each parent. The parents do not actually have the disease, but carry the Tay-Sachs gene and pass it on to the baby. If both parents have the abnormal Tay-Sachs gene, there is a one-in-four chance that their child will inherit the gene from both of them and have Tay-Sachs disease.
Tay-Sachs disease is most common in Ashkenazi Jews. About 1 in 30 people with this ancestry carry a copy of the gene. Some non-Jewish groups also have a higher chance of carrying the disease. They include people whose ancestors were French-Canadian, from the Louisiana bayou, or from Amish populations in Pennsylvania.
Two types of related conditions often are included in the definition of Tay-Sachs disease because they affect the same gene.
- A juvenile form usually appears between ages 2 and 5. The symptoms resemble those of classic Tay-Sachs disease, and death usually occurs by age 15 to 20. If the symptoms appear after age 5, the symptoms may be milder.
- An adult form, called late-onset Tay-Sachs, or LOTS, resembles the chronic form but first appears much later in life, between the teens and the 30s. This is very rare.
Other names for Tay-Sachs disease include Tay-Sachs sphingolipidosis, infantile ganglioside lipidosis, cerebromacular degeneration, GM2 gangliosidosis Type 1, and amaurotic familial infantile idiocy.
Early signs and symptoms of Tay-Sachs disease can include:
- Loss of muscle tone
- Exaggerated response to sudden noises
- Lack of energy
- Loss of motor skills, such as the ability to roll over, crawl, reach for things or sit up
In its advanced form, the disease causes a gradual loss of vision, deafness, seizures, gradual paralysis and dementia. Red spots may appear on the retina (inside the eye).
Tay-Sachs disease can be diagnosed before birth, through amniocentesis or chorionic villus sampling. In amniocentesis, a needle is inserted into the uterus through the abdomen and a sample of amniotic fluid is removed for testing. In chorionic villus sampling (CVS), a thin tube is inserted through the cervix and is used to extract a small sample of the placenta for testing. If you are considering having a child, you and your partner can have a blood test to see if you are carrying the Tay-Sachs disease gene. After birth, your doctor can do a blood test to see if your child has Tay-Sachs disease.
Tay-Sachs disease is a lifelong condition.
Genetic counseling before trying to get pregnant can help both parents understand the chances that they will have a child with Tay-Sachs disease. If both parents-to-be are carriers and the woman is pregnant, amniocentesis or chorionic villus sampling can determine if the fetus has the disease.
There is no effective treatment for Tay-Sachs disease. As with other fatal diseases, treatment is aimed at relieving symptoms and making the child and family comfortable.
When To Call a Professional
Any child or adult showing neurological problems should be evaluated by a doctor.
Classic infantile Tay-Sachs disease is a fatal disease and children with this disease usually die by age 5. Juvenile Tay-Sachs is also fatal, with death occurring in adolescence or early adulthood. The long-term outlook for the adult form is not known.
National Tay-Sachs and Allied Diseases Association
2001 Beacon St.
Brighton, MA 02135
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
National Organization for Rare Disorders (NORD)
55 Kenosia Ave.
P.O. Box 1968
Danbury, CT 06813-1968
March of Dimes Birth Defects Foundation
1275 Mamaroneck Ave.
White Plains, NY 10605