Tay-Sachs Disease

Medically Reviewed by Amita Shroff, MD on November 30, 2022
5 min read

Tay-Sachs disease is a rare, fatal disorder most commonly diagnosed in babies around 6 months of age.

There’s no cure for the disease, but scientists have a good idea of what causes it, how it worsens, and how to use genetic testing to screen for it early in pregnancy.

Researchers are working to make advances in gene therapy or bone marrow transplants that they hope will allow treatment of Tay-Sachs in the future

baby born with Tay-Sachs grows like they should until 3 to 6 months of age.

Around this time, parents might notice that their baby’s development starts to slow and their muscles weaken. Over time, the disease causes more symptoms in babies, including:

  • A loss of motor skills such as turning over, sitting, and crawling

  • A very strong reaction to loud noises

  • Trouble focusing on objects or following them with their eyes

  • Cherry-red spots, which can be identified with an eye exam, in the eyes

By age 2, most children with Tay-Sachs have started getting more serious problems. They can include:

  • Swallowing and breathing issues that keep getting worse

  • Seizures

  • Loss of mental function, hearing, and sight

  • Paralysis

Past age 3, there are few visible changes in children with Tay-Sachs, but their nervous system continues to get worse, often leading to death by age 5.

Defects in a gene called HEXA cause Tay-Sachs. (You can think of genes as “coding” that your parents pass along to you. Genes are in your cells, and they set your body’s traits -- everything from your eye color and blood type to your sex.)

Most people have two healthy versions of this HEXA gene, which gives instructions to your body to make an enzyme (a type of protein) known as Hex-A. This enzyme prevents the buildup of a fatty substance called GM2 ganglioside in your brain and spinal cord.

Some people have just one healthy copy of the gene, and they still make enough Hex-A protein to keep the brain and spinal cord healthy. But babies born with Tay-Sachs disease got a changed copy of the gene from both parents, so they don’t make any Hex-A protein. This is what makes them so sick.

Over time, GM2 ganglioside builds up in their nervous system and starts to cause damage.

The disease is very rare. It affects only about 1 in every 112,000 live births.

Anyone can be a carrier of a HEXA mutation, meaning they have just one defective copy of the HEXA gene.

But the chance of inheriting the disease is higher in certain groups because of a higher rate of carriers. About 1 in every 27 Jewish people in the United States is a carrier. Non-Jewish French Canadians living near the St. Lawrence River in Canada and in the Cajun community of Louisiana also have a higher incidence of Tay-Sachs.

If both parents are carriers of Tay-Sachs disease, there is a 25% chance that any child they have will get the disease.

Pregnant women can have a test to find out whether their unborn babies have the problem that causes Tay-Sachs. If the tests don’t find any Hex-A protein, the baby has Tay-Sachs. If the tests find Hex-A, the baby doesn’t have the disease.

These tests include:

  • Chorionic villus sampling (CVS). Your doctor takes a  small sample of the placenta with a needle or small tube and analyzes it. They can do this between the 10th and 12th weeks of pregnancy.

  • Amniocentesis. The doctor uses a needle to take a sample of the amniotic fluid that surrounds the baby and tests it.

To diagnose Tay-Sachs in a baby after it’s born:

  • Your doctor will ask you about your baby’s symptoms and your family history.

  • They’ll do a blood test to check Hex-A levels. 

  • The doctor will check the baby’s eyes. A cherry-red spot in the back of the eyes is a sign of Tay-Sachs. If it’s there, you may need to take your baby to specialists, such as a pediatric neurologist and an opthalmologist, for more tests.

Some of the specialists, treatments, and programs you might consider include:

  • Speech-language pathologists. They can provide ways to help your baby keep the suck-swallow reflex going as well as help you figure out when it is time to consider a feeding tube for your little one.

  • Neurologists. These specialists can help you manage your baby’s seizures with medication

  • Respiratory health. Specialists such as pediatricians and pulmonologists (doctors who treat lung and breathing problems) can recommend ways for parents to lower their child’s chance of lung infections.

  • Chest physiotherapy (CPT). Therapy to tap on the chest wall can help break up mucus in the lungs so your child can cough it up.

  • Feeding tubes. Your child may have trouble swallowing or may have breathing problems that include inhaling food or liquid into their lungs while eating. You can insert a feeding tube through your child’s nose into their stomach each time. Or a doctor may put in a tube during surgery.

  • Play and stimulation. You can help your child interact with the world through music, scents, and textures.

  • Massages. These can relax your baby.

  • Palliative and hospice care. These programs help manage quality of life for children with Tay-Sachs and their families.

You can have a blood test that analyzes your genes or the levels of the Hex-A protein in your blood to tell you whether you are a Tay-Sachs carrier.

If two people planning to have children find out that they’re both carriers, a genetic counselor can help them review the options for lowering the chances of having a baby with Tay-Sachs.

An even rarer type of Tay-Sachs is called “late onset” or “adult onset.” It can be hard to diagnose.

Like the version of the disease that affects infants, Tay-Sachs that starts later in life is caused by changes in the HEXA gene. Symptoms might start to appear anywhere from the teen years to adulthood.

Early symptoms often include clumsiness, trouble balancing, and muscle weakness in the legs. People with it may also have mental health issues.

This form of the disease affects each person differently. Late-onset Tay-Sachs doesn't always mean a shorter life span.