Tay-Sachs disease is a rare disorder that causes neurons to break down, especially those in the brain and spinal cord. The condition is classified as a lysosomal storage disorder because it involves a problem with lysosomal enzymes needed for proper cell functionality. Some experts also refer to Tay-Sachs disease as GM2 gangliosidosis because it involves a harmful build-up of gangliosides. The gene mutations that cause the condition are severe.
What is Tay-Sachs Disease?
Lysosomal enzymes are responsible for breaking down nutrients in cells, including fatty acids or gangliosides. In a person with Tay-Sachs disease, these lysosomal enzymes are missing or defective. A mutation within the HEXA gene causes this defect. The result is a build-up of fatty acids within the cells which becomes toxic, eventually destroying the cells and causing the symptoms associated with the condition. Tay-Sachs is an inherited disease, and the gene mutation must be present in both parents to occur in their offspring.
Risk Factors of Tay-Sachs Disease
Certain populations are more at risk than others of developing Tay-Sachs disease. These include people of Ashkenazi Jewish descent, members of the Old Order Amish population in Pennsylvania, people of French Canadian descent (specifically of the Quebec and New Brunswick regions), and the Cajun population of southern Louisiana. There is much discussion as to the reasons for this, and the scientific world has developed specific theories. Unfortunately, there is not yet a definitive reason why certain populations are more at risk. Men and women are at equal risk.
Infantile Tay-Sachs Disease
Tay-Sachs has three distinct categories: infantile, juvenile (subacute), and late-onset. The classificiation refers to the age of the individual when the production of lysosomes started being adversely affected by the mutant HEXA gene. Infantile Tay-Sachs is the most common form of the disease. Symptoms present at three to six months. Until then, children will usually appear healthy. However, because the body has never had effective production of lysosomes to properly clean the cells, this form is the most severe.
Juvenile (Subacute) Tay-Sachs Disease
Juvenile Tay-Sachs disease usually develops in children between the ages of two and ten. With this form of the disease, the gene mutation takes time to mature. For this reason, juveniles with Tay-Sachs present as healthy until symptoms develop. Typically, symptom development is more mild, at least at first, than those with the infantile form. Unfortunately, though, individuals are still too young at this age to easily recover from the damage that is done by the gene mutation.
Late-onset Tay-Sachs Disease
Late-onset Tay-Sachs is the least severe form of the disease. Symptoms usually begin to appear in the 30s. Until then, the body has been adequately producing lysosomes. As a result, symptoms of late-onset Tay-Sachs are generally mild and the body may be capable of combating the effects.
Symptoms of Tay-Sachs Disease
In infants, symptoms of Tay-Sachs disease include loss of motor skills such as turning over and raising the head, and a red spot forms on the retina. Muscle weakness, vision and hearing loss, and seizures also develop, as well as an exaggerated startle response to loud noises. The other forms of Tay-Sachs disease also present with a red spot on the retina. In these types of the disease, decreased muscle coordination, intellectual impairment, paralysis, speech problems, and mental illness often develop.
Diagnosis of Tay-Sachs Disease
The physical symptoms of Tay-Sachs disease are debilitating. Once a doctor suspects the condtion, he will conduct a blood test that indicates the presence of lysosomal enzymes. An eye exam will detect the spot on the retina; this tell-tale symptom will develop on everyone with the condition, regardless of age or classification.
Treatment of Tay-Sachs Disease
Treatments primarily involve alleviating symptoms. Medications can control seizures and reduce pain, and a feeding tube can help alleviate swallowing issues. Cellular degeneration often results in lung or respiratory infections that require breathing assistants. Physical therapy can ease joint pain and maintain a range of motion as large as possible throughout the disease’s progression. Current research is exploring gene therapy and enzyme replacement therapy, which could treat Tay-Sachs disease.
Prevention of Tay-Sachs Disease
Researchers have identified the gene responsible for Tay-Sachs disease, so genetic testing is an option for parents concerned about passing their genetic mutation onto their future children. The prevalence of the mutation in certain demographics also makes identification simpler. The best way to prevent Tay-Sachs disease is for two individuals with the mutation to avoid having biological children.
Prognosis for Tay-Sachs Disease
In infantile and juvenile Tay-Sachs disease, the prognosis is poor. Young bodies are incapable of recovering from damage done by the cellular degeneration. As a result, death usually occurs in those with infantile Tay-Sachs by age four; with the juvenile form, usually by age 15. Late-onset Tay-Sachs comes with a more favorable prognosis. There is a significantly increased risk of psychosis and muscle impairment. However, life expectancy may not decrease because of the disease.