Tay-Sachs disease is an inherited, life threatening condition where nerve cells in the brain and spinal cord degenerate and die. This leads to progressive neurological dysfunction.
A deficiency in the enzyme that breaks down a fatty substance in nerve cells, HexA, may cause Tay-Sachs disease. This deficiency stems from inheriting a mutated form of the gene — coding for the specific enzyme — that a person inherits from each parent.
Symptoms of the condition can vary, depending on the form of the condition the person acquires, but they may include muscle weakness and difficulties swallowing.
There is no cure for Tay-Sachs.
Keep reading to learn more about the prevalence, risk factors, cause, genetic pattern, symptoms, diagnosis, treatment, and outlook of Tay-Sachs disease.
Tay-Sachs disease is an inherited condition that involves progressive neurological degeneration.
There are three forms of the condition:
- Classic infantile: This is the most common form and can appear in infants around 6 months old.
- Juvenile: This form typically manifests in children aged 2 to 5 years, but it can occur anytime during childhood.
- Late-onset: This form typically occurs in adolescence or young adulthood, although some cases may appear later.
What other names does this condition go by?
Other names include:
- B variant GM2 gangliosidosis
- HexA deficiency
- GM2 gangliosidosis, type 1
- hexosaminidase A deficiency
- sphingolipidosis, Tay-Sachs
- hexosaminidase alpha-subunit deficiency (variant B)
Tay-Sachs disease is rare, as an estimated 5,000 individuals in the United States have it, according to the National Center for Advancing Translational Sciences.
In the general population, per the
People groups with a higher prevalence include:
- Ashkenazi Jewish heritage, which denotes the Jewish population of Central or Eastern European ancestry
- The Old Order Amish community in Pennsylvania
- Cajun community in Louisiana
- non-Jewish French Canadians who live near the St. Lawrence River
Anyone who belongs to any one of these groups may have a higher risk of developing this condition.
A deficiency of the enzyme beta-hexosaminidase (HexA) causes Tay-Sachs disease.
GM2 ganglioside is a fatty substance that is part of the body’s normal functioning, but it needs to be broken down. The body uses HexA to break it down.
When insufficient HexA is available, GM2 ganglioside builds up atypically in cells in the brain and spinal cord. This leads to cell degeneration and death. Triggering an immune response, these effects may cause damage to surrounding tissue as well as progressive damage to these structures over time.
In infantile Tay-Sachs, an individual typically has a complete absence of the enzyme. Whereas, in the juvenile or late-onset form of the condition, a person has some HexA enzyme activity.
The condition stems from a gene mutation on
People with one normal and another abnormal, or mutated, gene are healthy. But they are carriers of Tay-Sachs disease.
People inherit this condition in an autosomal recessive pattern.
When both parents are carriers — and their child inherits the mutated gene from them both — the child will have Tay-Sachs. If both parents are carriers, each child has a 25% likelihood of having the condition and a 50% risk of being a carrier, according to the
Below are the symptoms of the different forms of Tay-Sachs:
A baby develops normally in the first 6 months. Afterward, their development slows, and parents may notice changes in the child’s development.
Over time, an infant loses developmental skills they acquired, such as crawling and turning over. They also progressively have difficulty breathing and lose the ability to swallow.
At age 2, most children may experience recurrent seizures, as well as a loss of vision, mental skill, and muscle function.
Early symptoms may include:
- muscle weakness
Over time, children may lose the ability to:
- eat on their own
Additionally, they tend to have recurrent infections, and many experience seizures.
Early symptoms include muscle weakness in the legs and clumsiness.
After diagnosis, people may reflect back to their childhood and remember that they had signs, such as stuttering or a lack of athletic ability. Approximately 40% have mental health symptoms, such as psychosis or bipolar episodes.
Over time, individuals experience a slow-progressing decline in mobility. Many have swallowing and speech difficulties.
- History and physical examination: Doctors may note down neurological symptoms the infant is experiencing and look for signs of the condition.
- HexA blood tests: People with the infantile form will have no or extremely low levels of HexA, while those with the juvenile or late-onset form may retain levels of 10–15%.
- MRI scans: MRI scans and similar tests may provide images of the brain to assess for damage.
Molecular testing for mutations in the gene that codes for HexA can confirm a diagnosis. According to the
If both parents are carriers, they may wish to consult a genetic counselor before they conceive.
- managing seizures
- providing adequate nutrition
- protecting the airway for breathing
- managing infections
- offering early comprehensive occupational and physical therapy
Because Tay-Sachs involves progressive neurodegeneration — even with optimal care — individuals with the infantile form typically have a life expectancy of
People with the late-onset form frequently require mobility assistance. Also, their psychiatric symptoms often do not respond well to treatment. Progression of the condition often leads to a vegetative state and may lead to death in children aged 10 to 15 years.
Tay-Sachs disease is a condition that results in progressive neurological degeneration. While it is rare in the general population, it occurs more frequently in certain people groups, such as those of Ashkenazi Jewish heritage.
The condition results from a deficiency in HexA, an enzyme that prevents the accumulation of a fatty substance in the nerve cells. This happens when someone inherits a pair of mutated genes that code for the body’s HexA synthesis.
Symptoms vary with the form of Tay-Sachs, but they all involve a loss of mental or motor function. Typically, doctors diagnose this condition with an array of tests.
A molecular genetic test may be helpful in certain populations — people may want to consult with a genetic counselor to discuss what this test, and its results, may indicate.
There is no cure for the disease, so treatment focuses on providing support and increasing a person’s quality of life.