Tay-Sachs Disease

What is Tay-Sachs disease?

Tay-Sachs disease is a genetic condition that causes damage and, ultimately, the death of nerve cells (neurons) in your child’s brain and spinal cord. Symptoms like developmental delays, hearing and vision loss usually begin around 6 months of age.

It’s a progressive disease, meaning it gets worse over time. It leads to early death. There’s no cure, but treatment supports your child and keeps them comfortable.

What are the types of Tay-Sachs disease?

There are three types of Tay-Sachs disease. The type depends on when symptoms develop:

• Classic infantile: This is the most common form of Tay-Sachs disease. Children develop symptoms around 6 months of age.
• Juvenile: Children develop symptoms between the age of 5 and their teenage years. This form is very rare.
• Late-onset: Symptoms can appear during the late teen years or early adulthood. They can also develop after a person reaches 30 years old. This type may not affect your life expectancy. It’s also very rare.

The type of Tay-Sachs disease passes in families. For example, if one child inherits the infantile form, other children in the family aren’t at risk of late-onset Tay-Sachs disease.

How common is Tay-Sachs disease?

Studies estimate that approximately 1 in 300 people carry the genetic variant (mutation) responsible for Tay-Sachs disease. But the actual number of children born with Tay-Sachs disease is low, making the condition rare. Awareness, education and genetic testing help reduce the frequency of this condition among at-risk populations.

What are the symptoms of Tay-Sachs disease?

Symptoms of Tay-Sachs disease vary based on your child’s age. The disease progresses (gets worse) as your child grows. The most common sign of Tay-Sachs disease among children is missing developmental milestones for their age or losing skills they previously learned and mastered.

Classic infantile Tay-Sachs disease symptoms

Early symptoms (around 6 months) include:

• Muscle weakness.
• Difficulty turning over, sitting or crawling.
• Easily startled by loud noises.

As the disease progresses (before 1 year of age), symptoms include:

• Involuntary muscle twitching (myoclonic jerks).
• Seizures.
• Difficulty swallowing (dysphagia).
• Vision loss.
• Hearing loss.
• Cherry-red spot on their eyes.
• Respiratory infections.

Around 2 years old, the condition starts to take over completely. Your child may be in an unresponsive state. This means they don’t have much brain function. The age of death is usually between 2 and 4 years. Pneumonia is often the cause of death in infantile Tay-Sachs disease.

Juvenile Tay-Sachs disease symptoms

Children diagnosed with juvenile Tay-Sachs disease may experience the following symptoms after age 5:

• Muscle weakness or loss of muscle control.
• Frequent infections.
• Difficulty with speech and language (talking).
• Loss of previously learned skills.
• Mood and behavioral changes.
• Hearing and vision loss.
• Seizures.

The condition usually progresses into the teenage years and leads to early death during this time.

Late-onset Tay-Sachs disease symptoms

Adults diagnosed with late-onset Tay-Sachs disease may experience the following symptoms:

• Muscle weakness and spasms.
• Loss of coordination (ataxia) or the ability to walk.
• Difficulty with communication and swallowing.
• Psychosis or the development of mental health conditions.
• Late-onset types don’t usually affect a person’s life expectancy.

What causes Tay-Sachs disease?

A genetic change (mutation) of the HEXA gene causes Tay-Sachs disease.

The HEXA gene gives your cells instructions to make an enzyme (hexosaminidase A) that breaks down toxic substances in your body. If this enzyme isn’t available to do its job, a fatty substance collects in your cells. This damages and, ultimately, destroys cells within your brain and spinal cord, leading to symptoms of Tay-Sachs disease.

Is Tay-Sachs disease autosomal dominant or recessive?

Tay-Sachs disease is autosomal recessive. This means that two copies of the disease-causing genetic variant (change or mutation) to the HEXA gene need to be present for a Tay-Sachs disease diagnosis.

Each person has two copies of the HEXA gene. They get one from each of their biological parents.

Tay-Sachs disease happens when both parents have a mutated HEXA gene and pass it on to their children. As a result, neither copy of the baby’s HEXA gene works. Healthcare providers may refer to this condition as hexosaminidase A deficiency or hex A deficiency.

What does it mean to be a Tay-Sachs carrier?

A carrier is a person who has one working copy of the HEXA gene and one copy with a disease-causing variant. All humans inherit two copies of a gene, one from each biological parent to make a pair (one from the egg and one from the sperm). Carriers don’t have the condition or show symptoms, as their bodies can rely on the one working gene.

If two people who carry the genetic variant have a child, the child’s risk of developing the condition is as follows:

• A 25% (1 in 4) chance that the child won’t inherit any variant HEXA genes. The child won’t have Tay-Sachs disease or be a carrier.
• A 50% (1 in 2) chance that the child gets a variant gene from one parent. When this happens, the child will be a carrier but won’t have Tay-Sachs disease. As they’re a carrier, they may pass it on to their children.
• A 25% (1 in 4) chance that the child gets a variant gene from both parents. In this case, the child has Tay-Sachs disease.

What are the risk factors for Tay-Sachs disease?

A child is more at risk of developing Tay-Sachs disease if both of their biological parents carry the genetic variant. Anyone can be a carrier of the genetic variant. The condition is more common among people of French-Canadian, Eastern European or Ashkenazi Jewish descent, where approximately 1 in 30 people carry the genetic variant.

What are the complications of Tay-Sachs disease?

Tay-Sachs disease causes early death among children. As the condition progresses, a child’s life expectancy decreases.

How is Tay-Sachs disease diagnosed?

A healthcare provider will diagnose Tay-Sachs disease after a blood test. To perform this test, a healthcare provider will remove a small sample of blood from your child’s body, either their heel or a vein in their arm. Their provider will measure the level of the enzyme hexosaminidase A in the blood sample. In a child with classic Tay-Sachs disease, this protein is mostly or completely missing. People diagnosed with other forms of the disease have low levels of this enzyme.

A provider may also do an eye exam to see if the child has the classic cherry-red spot in their eye.

Can Tay-Sachs be diagnosed during pregnancy?

Two specialized tests can diagnose Tay-Sachs disease during pregnancy:

• Amniocentesis: Your healthcare provider will remove a sample of amniotic fluid (the fluid that surrounds a fetus in your uterus) to test it.
• Chorionic villus sampling (CVS): Your healthcare provider will remove a small piece of tissue from the placenta to test it.

Both tests look for the enzyme hexosaminidase A. If there’s a below-average amount of this enzyme in the testing samples, your healthcare provider will diagnose the fetus with Tay-Sachs disease. In addition, they may perform a genetic test on these samples to identify a mutation in the HEXA gene, which causes the condition.

How is Tay-Sachs disease treated?

Treatment for Tay-Sachs disease is supportive of your child’s symptoms. For example, your healthcare provider may prescribe medication to manage seizures. Other treatment measures include providing proper nutrition and hydration. Your child’s provider will make them as comfortable as possible.

In addition, your healthcare provider can help you and your family prepare for the loss of your child. They may recommend visiting a mental health professional or participating in a bereavement support group.

Treatment for late-onset Tay-Sachs disease

Treatment is available to help adults diagnosed with Tay-Sachs disease manage their symptoms, including:

• Using assistive devices or mobility equipment (wheelchair) to help with independence and navigation.
• Taking medication to manage mental health conditions or muscle spasms.
• Speech therapy.

Is there a cure for Tay-Sachs disease?

No, there isn’t a cure available for Tay-Sachs disease.

Can Tay-Sachs disease be prevented?

There’s no known way to prevent Tay-Sachs disease.

To learn more about your risk of having a child with a genetic condition like Tay-Sachs disease, talk to your healthcare provider about preconception counseling and genetic testing before getting pregnant. Your healthcare provider can help you plan for a future pregnancy.

What’s the outlook for Tay-Sachs disease?

Tay-Sachs disease is fatal for children. Your child’s care team will talk to you about end-of-life support and care. They’ll also offer guidance to help parents, caregivers and families manage the loss of a child. Many families find comfort in speaking with a mental health professional or participating in a bereavement support group.

Why is Tay-Sachs disease fatal?

Tay-Sachs disease is fatal because of damage and death of cells within your child’s brain and spinal cord. Cells have important jobs to keep our bodies working. With Tay-Sachs disease, a genetic variant affects the instructions your cells receive so they’re unable to do their jobs. This ultimately damages and destroys cells that are vital for your child’s survival.

The cause of death for many children with Tay-Sachs disease is a lung infection (pneumonia). As your child’s cells aren’t working as expected, their immune system can’t fight infections to keep your child healthy.

What is the life expectancy of someone with Tay-Sachs disease?

Children with infantile Tay-Sachs often pass away before the age of 5. Older children and teenagers diagnosed with juvenile Tay-Sachs disease have a life expectancy into early adulthood. Late-onset Tay-Sachs disease doesn’t directly affect an adult’s life expectancy.

Can you recover from Tay-Sachs disease?

No. Children can’t recover from Tay-Sachs disease. Treatment is available to keep your child comfortable and delay the progression of the condition.

How do I take care of my child diagnosed with Tay-Sachs disease?

The best way to care for your child is to manage their symptoms and keep them comfortable. Your care team will provide care and guidance on the following:

• Breathing: Many children with Tay-Sachs disease have breathing issues. They may develop lung infections because they have too much saliva and difficulty swallowing. Different medications, devices or body positioning can help your child breathe easier.
• Nutrition: A speech-language pathologist can help your child learn techniques to eat and drink. As swallowing gets worse, your child may need a feeding tube.
• Seizures: A neurologist can help you find the right treatment plan to manage seizures.
• Sensory stimulation: Children with Tay-Sachs disease have some sensory problems (issues with their five senses). You can try music, mobiles, relaxing scents and soft materials to help stimulate their senses.

When should I see a healthcare provider?

Talk to your provider if:

• You’re planning a pregnancy: If you’re thinking about becoming pregnant and are at high risk of passing on Tay-Sachs disease, talk to your provider. High risk can mean you or your partner have a history of Tay-Sachs in your biological families, or one or both of you is a Tay-Sachs carrier. Genetic testing is available for people who may face a higher risk of having a baby with Tay-Sachs.
• You have concerns during pregnancy: If you’re pregnant and have concerns about the health of the fetus, reach out to your provider.
• You notice symptoms in your child: If you’re worried your child is showing Tay-Sachs symptoms, such as not reaching developmental milestones on time, talk to their provider.

What questions should I ask my healthcare provider?

If you’re at high risk for having a baby with Tay-Sachs disease, ask your provider the following:

• I’m interested in preconception counseling, what do I need to do?
• How can I lower my risk of having a baby with Tay-Sachs disease?
• What if my partner and I are both carriers?
• What treatment do you recommend for my child?
• How do I keep my child comfortable?
• Can you recommend grief counseling or a bereavement support group?

Is Sandhoff disease similar to Tay-Sachs disease?

The symptoms and progression of Tay-Sachs disease are like those of Sandhoff disease. This is an inherited condition. Tay-Sachs disease involves the enzyme hexosaminidase A. Sandhoff disease involves hexosaminidase A and a second enzyme, hexosaminidase B.