Ataxia in the Cajun Gene Pool

One of the "genetic sharks" found in the gene pool of the Acadian descendants who inhabit southwest Louisiana is an inherited disease called ataxia. The hereditary neurological disorder has several different forms, some of which occur in Cajun families at rates up to 250% higher than in the general population of America.

The two most common types of the disease in Acadiana today are called Freidreich's Ataxia, which is a recessive form, and Marie's Ataxia, which is caused by a dominant gene. In cases of Freidreich's Ataxia, a child has a 25% chance to inherit a pair of recessive genes if both parents are otherwise healthy but genetic "carriers" of the disease. If a parent is afflicted with the dominant form, Marie's Ataxia, there is a 50/50 probability that his/her child will inherit the disease.

Genealogy searches by numerous affected families have shown the original ancestral links to be one particular Acadian family from Nova Scotia Thus, tracing hereditary connections is more than just a hobby for some members of the Cajun population.

The term "ataxia" literally means "lacking in muscular coordination, but the disease causes progressive deterioration of nerve cells in the cerebellum and spinal cord. Early symptoms, which generally appear in late adolescence but may not be apparent until later in life, include fatigue, slurred speech, stumbling gait, and hand uncoordination. The symptoms progress rapidly in some patients over a short period of 10-15 years, while it occurs more slowly over a 20-year span in others.

Numerous organizations have joined together to increase public awareness about ataxia and to provide affected families with useful information. The National Ataxia Foundation has an excellent website and recently sponsored activities for September 25, 2000's Ataxia Awareness Day. There is an active NAF Chapter in Louisiana, as would be expected with the large number of Cajuns who live in the statge. Beverly LeBlanc, an ataxia patient residing in Abbeville, serves as the local coordinator for the state chapter. The Louisiana group is presently planning a free "on-the-road" clinic with volunteers from the medical profession and other experts to offer help for ataxia victims and their families.

Why is ataxia concentrated to such a high level among the people of Acadiana? Cajuns are descended from a limited group of French-Acadian exiles who fled Canada and established new homes in southwest Louisiana during the 17th century. Intermarriages within the Cajun community were the social norm for many years, and the gene pool tended not to become very diversifies as a result. Thus, the genes for hereditary disorders such as ataxia were more likely to be passed on from one generation to the next among the people of the somewhat "closed" Cajun culture. As with Tay-Sachs disease among the Jewish population and sickle-cell anemia among African-Americans, the high incidence of ataxia among Acadiana's families has placed renewed emphasis on tracing ancestral connections and the importance of genetic screening.

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