Tay-Sachs Disease

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Every year, around 16 people in the United States are diagnosed with Tay-Sachs Disease. In this article, we’ll take a look at this condition including pregnancy screening and testing of children.

What is Tay-Sachs Disease?

Tay-Sachs Disease (TSD) is a rare neurodegenerative disease most commonly diagnosed in babies around 6 months. This fatal disorder can occur in children only if both parents carry the gene. TSD occurs when the Hexosaminidase A (HEXA) enzyme is not present in a fetus. HEXA is responsible for eliminating fatty protein and other harmful materials which can affect development. The less enzyme a person has, the more severe the disease and the earlier that symptoms appear.
Children born with TSD will often have issues with growth, hearing, sight, and mental development.

Tay-Sachs Disease will often lead to other health complications, such as lung infections. According to the National Health Service (England), the average life expectancy of a child born with the condition is between three and five years of age. 

Who is at risk of Tay-Sachs Disease?

Children born to parents who both carry the gene may be at risk of TSD. It’s thought that the highest risk group is those of Ashkenazi Jewish heritage. When both parents have the gene, there is a 50% chance that the child will also be a carrier but will not develop the disease. There is a 25% chance that the child will either not be a carrier and not develop the disease or will have the disease.

Symptoms

If TSD is not detected during pregnancy, it will usually only be diagnosed when a child begins to show symptoms which can include: 

• An inability to crawl or turn over
• The baby will stop smiling
• A loss of sight and a ‘red spot’ appearing behind the child’s eyes
• A loss of hearing
• An ability to reach for and grip items
• Seizures
• Muscle weakness
• Slurred speech
• Problems with mental development

These symptoms will usually manifest within the first few months of a baby’s life, but in some cases, can take a year or more to appear. It’s also possible for a child to have late-onset Tay-Sachs Disease. 

In this case, symptoms tend to be milder and may include no more than slight muscle weakness and some problems with sight and hearing.

Types

According to National Tay-Sachs and Allied Diseases, there are 3 forms of Tay-Sachs disease, distinguished by the general age of symptom onset:

Classic Infantile Tay-Sachs is the most common and severe form with symptoms appearing around the first 6 months of life. Symptoms include a loss of skills learned (regression), seizures, and loss of muscle and mental functions. Around 12 months, progressive seizures have been clinically found. 

Subacute Juvenile Tay-Sachs is a form with a range of severity, with symptoms appearing any time during childhood but most commonly between ages 2 and 5. Clinical studies found that patients with Subacute Juvenile Tay-Sachs showed a period of normal development until ages two to five years followed by a plateauing of skills and then loss of previously acquired developmental skills along with the onset of seizures and progressive global brain atrophy on neuroimaging. Spasticity, dysphagia, and seizures are present by the end of the first decade of life.

Late-Onset Tay-Sachs is the least severe form, with symptoms appearing in teenage years to adulthood. Symptoms may include clumsiness, muscle weakness, acute psychiatric disorders, including psychosis, and gradual loss of skills, often leading to the need for assistance with mobility. Intellect and behavior become impaired in some cases. The lifespan varies from shortened to unaffected.

Diagnosis & Tests

Tay-Sachs Screening

During pregnancy, parents who both carry the TSD gene are able to have their unborn child tested for a HEXA deficit between the tenth and twelfth weeks of the pregnancy. TSD screening involves a small sample of the placenta being taken by a needle. The sample will then be tested and, if HEXA is not detected, this means that the child will be born with Tay-Sachs disease.

Couples can find out if they carry the TSD gene through a simple blood test which will determine the presence of the HEXA gene. It’s recommended that this test is carried out if relatives of the couple are known to be carriers.

For couples who are aware that they carry the gene and wish to start a family, there are options available such as assisted reproductive technologies, and IVF. Couples are encouraged to discuss these options with a genetic counselor. 

Treatment & Care

Can Tay-Sachs Disease Be Cured?

Unfortunately, there is currently no cure for TSD. In most cases, the condition will prove fatal by the time a child is five years old. The disease can, however, be managed through pain relief and medication to control muscle spasms and seizures. There is a lot of research underway regarding the condition, and hopefully, experts will be able to find a cure.
For Infantile Tay-Sachs disease, death from respiratory complications usually occurs between ages two and three years, although the use of a gastrostomy tube to minimize aspiration events and improved pulmonary hygiene with the use of vibrating vests has extended the lifespan of infantile patients to between five and seven years.

Advice for parents

Caring for a child with Tay-Sachs Disease can be extremely challenging, particularly in the later stages when the child may suffer extreme disabilities. Parents’ doctors or medical professionals will provide support regarding the management of the symptoms in order to keep their children as safe and comfortable as possible. There are also support groups available for parents, including the National Tay-Sachs and Allied Diseases Foundation and the March of Dimes Foundation – both of which offer parents valuable advice and ongoing support. 

While there’s no doubt that Tay-Sachs Disease can be devastating for parents and the children affected, it’s important to understand that this is a rare condition. Even when both parents carry the gene, a child can still be born without the disease. Parents who carry the gene and are concerned about the risks should contact their medical professionals in order to arrange screening during pregnancy.

Things to Avoid 

For individuals with Infantile TSD, avoid positions that increase the risk of choking during feedings, seizure medication dosages that result in excessive sedation.

For individuals with Subacute Juvenile TSD, avoid situations that increase the likelihood of contractures or pressure sores, such as extended periods of rest, environments, and situations that heighten the risk of falls.

For individuals with Late-Onset TSD, avoid circumstances that increase the risk of falls, psychiatric medications that have been associated with disease worsening (e.g., haloperidol, risperidone, and chlorpromazine).