Researchers in the Department of Neurology at the University of Medicine and Dentistry of New Jersey have determined that some members of the Whipple family suffer from a disease known as Machado-Joseph Disease (MJD). MJD is also known as Spinocerebellar Ataxia 3 (SCA3), so named because it was the third of many such ataxias to be identified. “Ataxia” is a general term referring to lack of muscle control.
MJD is characterized by clumsiness and weakness in the arms and legs, spasticity (continuous, uncontrollable muscle contractions), a staggering lurching gait (easily mistaken for drunkenness), difficulty with speech and swallowing, involuntary eye movements, double vision, and frequent urination. Some patients have ystonia (sustained muscle contractions that cause twisting of the body and limbs, repetitive movements, abnormal posture, and/or rigidity) or symptoms similar to those of Parkinson’s disease. Others have twitching of the face or tongue, or distinct bulging eyes. Almost all MJD patients experience vision problems, including double vision (diplopia) or blurred vision, loss of ability to distinguish color and/or contrast, and inability to control eye movements.
MJD is an inherited, autosomal dominant disease (one affected arent can pass it to the child). People with a defective gene have a 50 percent chance of passing the mutation to each child. If a child inherits the defective gene, s/he will develop symptoms of the disease. The disease belongs to a class of genetic disorders called triplet repeat diseases in which there is an extensive abnormal repetition of three letters of the DNA genetic code. In MJD, the code “CAG” is repeated within a gene located on chromosome 14q. The gene produces a mutated protein called
ataxin-3, that accumulates in certain cells of the brain. These protein accumulations interfere with the normal operation of cells, causing them to degenerate and die.
While MJD is incurable, many of its symptoms can be treated. The drug Levodopa can help patients who show Parkinson features. Antispamodic drugs such as baclofen can help reduce spasticity; Botulinum toxin (which can have severe side affects) is used to treat severe spasticity as well as some symptoms of dystonia. Speech problems (dysarthria) and dysphagia (difficulty in swallowing) can be treated with medication and speech therapy. Wearing prism glasses can reduce blurred or double vision. Eye surgery has short-term benefits because of the progressive degeneration of eye muscles. Physiotherapy can help cope with disability caused by gait problems and physical aids, such as walkers and wheelchairs, can assist with everyday activities. Problems such as sleep disturbances, cramps, and urinary dysfunction can also be treated with medications and medical care.
MJD is usually diagnosed by a neurologist, after s/he does a thorough clinical examination. Even in a person who has a positive family history for MJD, it is possible for other things to cause confounding symptoms. Fortunately, a definitive diagnosis can now be made with a simple genetic test.
Because MJD is only one of a large category of triplet repeat diseases, there is much research aimed at understanding the mechanism of disease development, as well as approaches to possible treatments. And it is reasonable to presume that a treatment breakthrough developed for any one of these disorders would have immediate positive effect on another.
For information on MJD and other neurological disorders, research programs funded by NIH, or information on ongoing studies for which one may qualify, see the National Institute of Neurological
Disorders and Stroke’s Brain Resources and Information Network at: BRAIN, P.O. Box 5801. Bethesda, MD 20824, (800) 352-9424
For additional information on ataxias, a fact sheet on SCA3, ongoing research programs, or family support, contact the National Ataxia Foundation (NAF), 2600 Fernbrook Lane North, Suite 119,
Minneapolis, MN 55447-4752, firstname.lastname@example.org, Tel: 763-553-0020, Fax: 763-553-0167. http://www.ataxia.org