Juvenile Tay-Sachs
Tay-Sachs is caused by the absence of a vital enzyme called Hexosaminidase-A (Hex-A). Like most storage disorders, Tay-Sachs disease occurs along a continuum. From infantile, the most severe form in which there is virtually complete absence of Hex-A, to Juvenile, which affects older children to Late Onset Tay-Sachs (LOTS), impacting even older children or teens and adults who have very low or moderately low levels of Hex-A. Without any Hex-A, a fatty substance or lipid accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing build-up causes progressive damage to the nerve cells, gradually leading to their degeneration and death. Individuals who have low levels of Hex-A, have a slower onset of symptoms and progression of disease, compared to those with Classic Infantile Tay-Sachs. It is important to note that within each form of Tay-Sachs disease, there is a range of severity and each person’s experience with the disease is distinctive.
Children with Juvenile Hex-A deficiency usually develop symptoms between the ages of 2 and 5 years that resemble the symptoms of the Classic Infantile form. Though the course of the disease is slower, end stages generally occur in late adolescence or into the 20s. If starting after age 5, symptoms may be milder than those that characterize earlier onset forms. Mental abilities, vision and hearing remain intact, but affected individuals develop ataxia (lack of coordination), dysarthria (slurred speech), muscle atrophy (weakness), muscle cramps, tremors, unsteady gait and sometimes mental illness. Again, the differences in age of onset and severity of symptoms shows the broad range of this disease and why it continues to be a mystery to even many seasoned medical professionals.
Additional Informational Links
The following online resources may be helpful in learning more about Juvenile Tay-Sachs Disease or locating support:
National Institute of Neurological Disease and Stroke
National Organization of Rare Diseases
Online Mendelian Inheritance in Man