Late-Onset Tay-Sachs Disease
Late-onset Tay-Sachs (LOTS) disease is a rare form of Tay-Sachs disease, a lysosomal storage disorder caused by the absence of the enzyme Hexosaminidase A (Hex-A). LOTS was first recognized in the 1970s during routine Tay-Sachs carrier screening.
Investigators have discovered very low levels of Hex-A in older children and adults whose symptoms include ataxia (lack of coordination), dysarthria (slurred speech) and muscle atrophy (weakness). Many of these individuals had been misdiagnosed with other muscular or neurological disorders. It is not uncommon for affected people to go many years before receiving an accurate diagnosis of LOTS. Accurate diagnosis can be made through enzyme assay and DNA analysis.
The symptoms typically presents in adolescence, with dysarthria, proximal (trunk) muscle weakness, tremor and ataxia. Muscle cramps, especially in the legs at night, and fasciculations (muscle twitching) are common. Not all symptoms are present in every individual affected by the disease; weakness of the proximal muscles, however, is a symptom common to all. Examples of trunk muscle weakness may include difficulty rising from a seated position, trouble getting out of bed, struggling to balance while getting dressed. Symptoms of manic-depression or psychotic episodes may be present in about 30% of affected persons.
As a recently recognized rare form along the Tay-Sachs continuum, the course of LOTS is not completely known. Life expectancy is probably not reduced. Affected individuals understandably report feelings of isolation and uncertainty as to what to anticipate as the disease progresses. Social and academic difficulties, resulting from the physical and psychiatric manifestations of the disease, are also a concern.
| Fact: LOTS affects adults, not infants as in classical Tay-Sachs, who display a significantly reduced level of Hex-A, rather than a complete absence of the enzyme. |
Additional Informational Links
The following online resources may be helpful in learning more about Late Onset Tay-Sachs Disease or locating support:
National Institute of Neurological Disease and Stroke
National Organization of Rare Diseases
Online Mendelian Inheritance in Man