Lafayette (LA), Daily Advertiser, March 5, 1999

ATAXIA, A MATTER OF HEREDITY

The Genetic Disease Prevalent Among Cajuns Robs People of the Ability to Move

by Judy Stanford

When the early settlers arrived here in the mid-1700s from Canada, they were a small population living in isolation from the rest of the world. When children came of age, they found only a small number of eligible candidates for marriage, so it was not unusual in those early days for cousin to marry cousin.

It was just part of life in the wilderness back then, but the effects of the practice have reached into present-day generations.

"We have a high incidence of-the genetic disorders here," said New Orleans neurologist Dr. Michael Wilensky. "Part of the reason is because of intermarriage among Cajuns during the early years. It enhances a recessive gene." It was not until 1904 that it became illegal to marry a first cousin.

Among the genetically transmitted diseases prevalent in the Acadian population is a neuromuscular degenerative disease called ataxia. Wilensky is the medical director of the Louisiana Chapter of the National Ataxia Foundation.

The word, ataxia, means simply, "off-balance," Wilensky explained. "If you're drunk, you're ataxic. But being drunk is a temporary disease. These are progressive degenerative diseases." There are several forms of ataxia. Among the more common forms of the condition found in south Louisiana are Friedreich ataxia, Charcot-Marie-Tooth, French Settlement disease and Ataxia Telangiecstasia.

Denise Drake of New Orleans, state chapter president of the National Ataxia Foundation, first noticed symptoms of Friedreich ataxia when she was about 10 years old.

"You slowly lose your abilities," she said. "Very often our minds think faster than our bodies will move and that's a bit aggravating."

Now 40, Drake is wheelchair-bound and needs help with showering and dressing.

The condition, which is often misdiagnosed as multiple sclerosis and other diseases that affect coordination, slowly robs its victims of the ability to walk, to stand, to move at all. Other problems often accompany some forms of ataxia, including diabetes, heart problems, curvature of the spine and deafness. Many ataxia victims don't survive beyond their 40s, although modern treatments have changed those statistics somewhat for the better.

"The hardest adjustment to living with this is the fact that it's degenerative," Drake said. "Being clumsy-looking, people thinking you're drunk or on drugs, getting horrible stares, children and even adults making fun."

Unlike diseases like Alzheimer's that can also bring on dementia, ataxia leaves the mind untouched.

"When ataxia patients develop movement problems and wind up in nursing homes," Wilensky said, "95 percent of these patients have all their mental faculties. That's one of the worst aspects of this disease."

Although the symptoms of ataxia can be relieved to some degree with medication, there is no cure. The only defense is prevention and education.

Toward that end, the state chapter of the Ataxia Foundation periodically holds screening clinics like the one to be held tomorrow in Abbeville. Among the professionals who volunteer to staff the clinics are neurologists, geneticists, physical, occupational and speech therapists and audiologists. In addition to looking for symptoms of the onset of the disease, doctors take blood samples for genetic testing.

Geneticists have isolated a defective gene in ataxia patients that prevents them from producing adequate amounts of a certain newly discovered protein called frataxin, said Bronya Keats who holds a doctorate in genetics and serves as the director of the Center for Human Genetics at LSU Medical School in New Orleans. She is also the director of the Center for Acadian Genetics and Hereditary Health Care. Keats and Wilensky will both be on hand for the Abbeville clinic.

Not everyone who carries the gene develops ataxia. Drake is one of four siblings, but is the only one who has the condition. But it is possible for carriers to pass it on to their children. In the case of the recessive gene that causes Friedreich ataxia, the condition manifests itself only if both parents have the gene.

Forms of ataxia caused by the dominant form of the gene strike later in life and cause some of the same problems as Friedreich ataxia, plus some others, including an inability to swallow, which can lead to death by choking. Only one parent need carry the dominant gene to cause ataxia in offspring.

Genetic solutions to this genetic problem are the ultimate goal, Wilensky said. "But we're far from that."

That's why identifying the carriers of the disease is important. "We try to spread the message," Wilensky said, "that the only way to stop it is to prevent it. If you are at risk, you want to become educated and make decisions as to whether or not you would have children and pass it on."

How is ataxia inherited?

Recessive hereditary ataxia

In recessive types of ataxia, like Friedreich ataxia, parents rarely exhibit symptoms, but they each carry a recessive gene which may cause ataxia in their offspring. The recessive gene may lie dormant for generations until two people with the defective gene have children. The symptoms usually appear in the first or second decade.

Each of the children of parents carrying a recessive gene has the following genetic odds: a 25 percent chance of being free, a 50 percent chance of being a carrier without showing symptoms, and a 25 percent chance of having the disease.

Dominant hereditary ataxia

Dominant ataxia is passed on as a hereditary disease through defective genes directly from parent to child. Each child born of a parent with dominant ataxia has a 50 - 50 chance of developing ataxia. Symptoms usually appear between the ages of 20 and 40. If a child does not develop ataxia, his or her children in turn cannot become afflicted, and future generations are free of the disease.

--National Ataxia Foundation

Facts about Ataxia

• Ataxia first appears with symptoms of a stumbling or drunken walk, uncoordinated hand movements and slurred speech. Symptoms progress quite rapidly in some people over a period of 10 to 15 years, or slowly in others over a soon of 20 or more years. The person may require the use of a wheelchair. There is no known cure.
• Ataxia is difficult to diagnose and there may not be a prenatal test which can determine if the disease exists in an unborn child.
• Ataxic is commonly misdiagnosed as multiple sclerosis.
• Ataxia and related disorders affect an estimated 150,000 persons of all ages and both sexes in the United States. There are many more at risk for the disease who, as yet, have no symptoms.
• Hereditary ataxia can also be classified by the genetic patterns of inheritance, either recessive or dominant. The population of people with hereditary ataxia is large, diverse and difficult to locate and study, primarily because of the inheritance patterns, the variety of clinical symptoms, and neurologic findings exhibited.
• Ataxia is often fatal because of complications, including heart problems and breathing difficulties.

National Ataxia Foundation