We fund advanced research into a genetic disease that is 100% fatal in all children. They ususally did by age 5, never have walked a step nor spoken a single word Tay-Sachs disease (TSD) is hereditary. A mutation in the Hex-A gene causes the body to have no or very low levels of the Hex-A enzyme. Without Hex-A, cells (especially nerve cells in the brain) are unable to break down fatty waste products. The waste products begin to build up inside the cells causing it to swell and eventually die. Since the Hex-A gene was isolated in 1985 it is believed there are between 75 and 100 different mutations that can cause TSD. The various mutations can result in Infantile (most common), Juvenile or Late On-Set. The Infantile and Juvenile forms of the disease have never been treatable and have always resulted in death. The Late On-Set form works at a slower pace, but continues to progress as cells clog with waste product. The pace of the disease is directly related to the amount of Hex-A the affected person has. Infantile cases generally have no Hex-A present and therefore the disease progresses very quickly ï¿¿ often resulting in death by age 3. The damage caused by the gene mutation actually begins to occur in the fetal stages of development, but symptoms are often not evident for months after birth. Most TSD sufferers appear totally normal at birth and for some time after that. One of the most insidious features of Tay-Sachs disease is it often strikes families with no prior history of the disease. Large and diverse family trees allow the carriers of the Tay-Sachs disease to go without expression for generations until unexpectedly a child is diagnosed and the family submits to carrier testing.