Rare childhood genetic disorder with progressive deterioration of nerve cells and of mental and physical abilities.Encyclopedia Entry for Tay-Sachs Disease :Tay-Sachs disease. Tay-Sachs disease occurs when the body lacks hexosaminidase A. This is a protein that helps break down a group of chemicals found in nerve tissue called gangliosides. Without this protein, gangliosides, particularly ganglioside GM2, build up in cells, often nerve cells in the brain. Tay-Sachs disease is caused by a defective gene on chromosome 15. When both parents carry the defective Tay-Sachs gene, a child has a 25% chance of developing the disease. The child must receive two copies of the defective gene, one from each parent, in order to become sick. If only one parent passes the defective gene to the child, the child is called a carrier. They will not be sick, but may pass the disease to their own children. Anyone can be a carrier of Tay-Sachs. But, the disease is most common among the Ashkenazi Jewish population. One in every 27 members of the population carries the Tay-Sachs gene. Tay-Sachs is divided into infantile, juvenile, and adult forms, depending on the symptoms and when they first appear. Most people with Tay-Sachs have the infantile form. In this form, the nerve damage usually begins while the baby is still in the womb. Symptoms usually appear when the child is 3 to 6 months old. The disease tends to get worse very quickly, and the child usually dies by age 4 or 5. Late-onset Tay-Sachs disease, which affects adults, is very rare.Symptoms may include any of the following: Deafness Decreased eye contact, blindness Decreased muscle tone (loss of muscle strength), loss of motor skills, paralysis Slow growth and delayed mental and social skills Dementia (loss of brain function) Increased startle reaction Irritability Listlessness Seizures.The health care provider will examine the baby and ask about your family history. Tests that may be done are: Enzyme exam of blood or body tissue for hexosaminidase levels Eye exam (reveals a cherry-red spot in the macula ).There is no treatment for Tay-Sachs disease itself, only ways to make the person more comfortable.The stress of illness may be eased by joining support groups whose members share common experiences and problems. Cure Tay Sachs Foundation -- www.curetay-sachs.org National Tay-Sachs and Allied Diseases Association -- www.ntsad.org Genetic Alliance -- www.geneticalliance.org March of Dimes -- www.marchofdimes.org.Children with this disease have symptoms that get worse over time. They usually die by age 4 or 5.Symptoms appear during the first 3 to 10 months of life and progress to spasticity , seizures, and loss of all voluntary movements.Go to the emergency room or call the local emergency number (such as 911) if: Your child has a seizure of unknown cause The seizure is different from previous seizures The child has difficulty breathing The seizure lasts longer than 2 to 3 minutes Call for an appointment with your provider if your child has other noticeable behavioral changes.There is no known way to prevent this disorder. Genetic testing can detect if you are a carrier of the gene for this disorder. If you or your partner is from an at-risk population, you may wish to seek genetic counseling before starting a family. If you are already pregnant, testing the amniotic fluid can diagnose Tay-Sachs disease in the womb.GM2 gangliosidosis - Tay-Sachs; Lysosomal storage disease - Tay-Sachs disease.Central nervous system and peripheral nervous system Central nervous system and peripheral nervous system.Kwon JM. Neurodegenerative disorders of childhood.