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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. Treatment involves supportive measures, such as providing adequate nutrition, maintaining hygiene, preventing infections, and providing musculoskeletal support. Even with optimal care, the typical life expectancy for individuals with the infantile form is 4 to 5 years. Keep reading to learn more about the prevalence, risk factors, cause, genetic pattern, symptoms, diagnosis, treatment, and outlook of Tay-Sachs disease. Overview Share on Pinterestmrs/Getty ImagesTay-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 gangliosidosisHexA deficiencyGM2 gangliosidosis, type 1hexosaminidase A deficiencysphingolipidosis, Tay-Sachshexosaminidase alpha-subunit deficiency (variant B)TSD How common is this condition 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 National Library of Medicine (NLM), it affects approximately 1 in 1,000,000 live births, and the carrier frequency is 1 in 250. A carrier is a person who does not have the condition but can pass it on to their children. People groups with a higher prevalence include:Ashkenazi Jewish heritage, which denotes the Jewish population of Central or Eastern European ancestryThe Old Order Amish community in PennsylvaniaCajun community in Louisiananon-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. Causes 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. Genetic and inheritance pattern of the condition The condition stems from a gene mutation on chromosome 15 that codes for HexA production. Every person has two copies of this gene, one from each parent. If at least one copy of the gene is normal, their body makes enough HexA. 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 NLM. Symptoms Below are the symptoms of the different forms of Tay-Sachs: Classic infantile 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. Juvenile Early symptoms may include:muscle weaknessclumsinessincoordination Over time, children may lose the ability to:eat on their owncommunicatewalk Additionally, they tend to have recurrent infections, and many experience seizures. Late-onset 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. Diagnosis The diagnostic process may require: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 National Human Genome Research Institute, this procedure detects about 60% of carriers in the general population and about 95% of carriers with an Ashkenazi Jewish background. If both parents are carriers, they may wish to consult a genetic counselor before they conceive. Treatment There is no cure for Tay-Sachs disease. Treatment typically involves supportive measures that may include:managing seizuresproviding adequate nutritionprotecting the airway for breathingmanaging infectionsoffering early comprehensive occupational and physical therapy Outlook Because Tay-Sachs involves progressive neurodegeneration — even with optimal care — individuals with the infantile form typically have a life expectancy of 4 to 5 years. Death is normally due to recurrent infections. 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. Summary 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. Last medically reviewed on September 20, 2022Body AchesGeneticsPain / AnestheticsPalliative Care / Hospice CarePediatrics / Children's HealthMedically reviewed by Heidi Moawad, M.D. — By Mary West on September 20, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? 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