Tay-Sachs and Sandhoff diseases
Tay-Sachs and Sandhoff diseases are rare, inherited diseases that affect a baby’s central nervous system (the brain and spinal cord). The central nervous system controls how the body works.
Sandhoff disease is a severe form of Tay-Sachs. Babies with Tay-Sachs have none or not enough of an enzyme (protein) called hexosaminidase A.
Babies with Sandhoff disease have no hexosaminidase A and hexosaminidase B enzymes. Both enzymes break down fatty substances in cells, including brain cells. Without enough of these enzymes, fatty substances build up and slowly destroy brain cells, until the nervous system stops working.
Over time, Tay-Sachs and Sandhoff diseases cause nerve cells in the brain and spine to die. Some forms of each disease can affect babies and cause death. About 16 people are diagnosed with Tay-Sachs disease each year in the United States.
What causes Tay-Sachs and Sandhoff diseases?
Both diseases are passed from parent to child through genes. A gene is a part of your body’s cells that stores instructions for the way your body grows and works. Genes come in pairs—you get one of each pair from each parent.
Sometimes the instructions in genes change. This is called a gene change or a mutation. Parents can pass gene changes to their children. Sometimes a gene change can cause a gene to not work correctly. Sometimes it can cause birth defects or other health conditions.
You have to inherit a gene change from both parents to have these diseases. If you inherit the gene change from just one parent, you have the gene change but not the disease. When this happens, you’re called a carrier. A carrier has the gene change but doesn’t have the disease.
If you and your partner both carry the gene change for Tay-Sachs, your baby may get two gene changes (one from each of you) and have the disease. It works the same way for Sandhoff disease. If both you and your partner are carriers (you both have the gene change), there is:
- A 1-in-4 chance (25 percent) that your baby can have the disease
- A 1-in-4 chance (25 percent) that your baby won’t have the disease and won’t be a carrier
- A 1-in-2 chance (50 percent) that your baby won’t have the disease but will be a carrier
If a blood tests shows that you or your partner is a carrier for Tay-Sachs or Sandhoff disease, you may want to meet with a genetic counselor. This is a person who is trained to help you understand how genes, birth defects and other medical conditions run in families, and how they can affect your health and your baby’s health.
Are some babies more likely to have these diseases than others?
Yes. Tay-Sachs is more common in people from certain ethnic groups. An ethnic group is a group of people, often from the same country, who share language or culture.
Tay-Sachs is more common in these ethnic groups:
- Central and Eastern European Jewish (also called Ashkenazi Jews)
- French-Canadian groups in Quebec, Canada
- Louisiana Cajun
- Old Order Amish of Pennsylvania
Sandhoff disease isn’t as strongly linked to ethnic groups as Tay-Sachs. It’s rare among Jewish people and seems to be more common in these groups:
- Creole of northern Argentina
- Metis Indians in Saskatchewan, Canada
If you or your partner is part of these ethnic groups, or you have a family history of Tay-Sachs disease or Sandhoff disease, tell your health care provider. You and your partner can have a blood test to see if you carry the gene mutation that causes these diseases.
How do you know if your baby has Tay-Sachs or Sandhoff disease?
Your health care provider may use prenatal tests to diagnose Tay-Sachs or Sandhoff disease before birth. Prenatal tests are medical tests you get during pregnancy. They help your provider find out how you and your baby are doing. Your provider may use these prenatal tests to diagnose Tay-Sachs or Sandhoff diseases:
- Amniocentesis (also called amnio). This this test takes some amniotic fluid from around your baby in the uterus. The test checks for birth defects and genetic conditions in your baby. You can get this test at 15 to 20 weeks of pregnancy.
- Chorionic villus sampling (also called CVS). This test checks tissue from the placenta to see if a baby has a genetic condition, like Tay-Sachs or Sandhoff disease. You can get CVS at 10 to 12 weeks of pregnancy.
If your baby develops problems hearing, seeing or moving after birth, your baby’s provider may use a physical exam and blood tests to diagnose the diseases.
Are there different types of each disease?
Yes. They’re named depending on when the disease affects a person. The classic (also called infantile) type affects babies and is the most common type of each disease. The juvenile type starts during childhood. Other types of these diseases are less common, but may affect older children, teens or adults.
Classic Tay-Sachs and classic Sandhoff diseases. These diseases affect a baby when he’s young. Babies with classic Tay-Sachs disease usually die by the time they’re 4 years old. Babies with classic Sandhoff disease usually die by the time they’re 3 years old.
A baby with classic Tay-Sachs or classic Sandhoff disease starts to develop normally in the first few months of life. Signs and symptoms of the disease usually appear by about 6 months, when the baby slowly stops smiling, crawling, turning over and reaching out. Your baby’s health care provider may see cherry-red spots in your baby’s eye during an eye exam.
Over time, a baby continues to lose skills and develops other health problems, including:
- Breathing problems
- Hearing loss
- Intellectual disabilities. These are problems with how the brain works that can cause a person to have trouble or delays in physical development, learning, communicating, taking care of himself or getting along with others.
- Paralysis. This is when you can’t feel or move one or more parts of your body.
- Seizures. This is when the whole body or parts of the body move without control.
- Swallowing problems
- Vision loss, leading to blindness
Juvenile Tay-Sachs and juvenile Sandhoff diseases. These diseases can begin anytime during childhood. Children with these conditions usually die by the time they’re 15 years old. They usually show signs or symptoms when they’re 2 to 5 years old, including:
- Being clumsy
- Having slurred speech
- Having weak muscles or muscle cramps
Over time, these children have more health problems. They eventually can’t walk, eat by themselves or communicate. They may have seizures and may be more likely than other children to get lung infections, like pneumonia.
Are there any treatments for Tay-Sachs and Sandhoff diseases?
There is no cure for these diseases, but medicines and healthy eating can help manage them. Medicines can treat pain, seizures and twitching muscles. Some children need a feeding tube, a small, soft, plastic tube placed through the nose or mouth into the stomach. You can give food and medicine to your baby through the tube when she can’t take them by mouth.
See also: Genetic counseling
Last reviewed: May, 2014