Is Cajun in the genes?

06/30/05

LSU professor teams with LSU Health Sciences Center to investigate genetics of Louisiana's Acadian people

In Longfellow's famous poem Evangeline, the heroine of the title and her betrothed, Gabriel, are torn apart when the British forcibly remove the Acadian people from Nova Scotia, scattering them across the East Coast and into the swamps of South Louisiana. Though the story is based on actual events, Evangeline, Gabriel and their family and friends are fictional. However, had they once been living, breathing humans with flesh, blood and genes LSU scientist Mark Batzer could discover more about them than Longfellow could have ever imagined.

Indeed, Batzer might even be able to locate their living descendants and determine what traits they inherited from their French forebears.

Batzer, the George C. Kent Professor of Life Sciences at LSU, has been working for more than a decade with researchers from the LSU Health Sciences Center and the Tulane Health Sciences Center in New Orleans to trace, analyze and better understand the genetics of the Acadian people in Louisiana.

The project is a massive one, with a variety of offshoots, or sub-projects, funded by millions of dollars from a variety of sources, including the National Institutes of Health and the Louisiana Board of Regents Health Excellence Fund. Batzer has been primarily involved in two key areas of investigation: a population genetics study the study of the genetic structure or architecture of the Acadian population as a whole and a study of the genetic underpinnings of certain disorders found in or at higher rates in the Acadian population.

The history of the Acadian people, known as "Cajuns" in Louisiana, makes them a particularly good focus group for genetic study.

In the 18th century, Acadians were French-descended residents of Nova Scotia. They were expelled from Canada by the British in 1755 and began drifting into Louisiana around 1763, settling along the Mississippi River and Bayous Lafourche, Teche and Vermilion in South Louisiana. There, they have remained, a geographically isolated population marrying and raising families for more than 200 years. Indeed, it is estimated that there are close to half a million Louisiana residents with Acadian blood.

Much of the work on the Acadian genetics project began decades ago with researchers from the LSU Health Sciences Center in New Orleans. A key player in the research was Bronya Keats, who is now chair of the Department of Genetics and director of the Center for Molecular and Human Genetics at the Health Sciences Center. Contained within the Center for Molecular and Human Genetics is a program called the Center for Acadiana Genetics and Hereditary Health Care.

Keats began her research in the 1980s, looking into a genetic disorder called Friedreich's Ataxia, or FA, which is found in about one out of every 20,000 members of the Acadian population. About one in 70 members of the Acadian population is a carrier.

"With this disease, children begin to lose coordination of their limbs at about the age of 10 years, and by the time they are in their mid-20s, they are in a wheelchair," Keats explained.

Several years after beginning her study of FA in Acadian families, Keats began collaborating on another project that had been initiated by one her colleagues, Dr. Mary Kay Pelias. This research project focused on a disorder called Usher Syndrome, which can cause hearing and vision impairment.

Usher Syndrome, like FA, has a frequency of about one in 20,000 in the Acadian population. Eager to find out more about these inherited disorders, other scientists began joining the Acadian research effort.

"We were trying to identify the gene for Usher Syndrome," said Batzer, who began working on the project around 15 years ago. "There are a lot of different variants of that syndrome, but one is essentially unique to Acadians."

Batzer said that research into the genetic history of the Acadians has been aided by excellent historical record keeping by families and churches. In addition, he said, the people themselves are friendly, eager to learn more about their history, and, most important, eager to help out.

"This is more than just scientific research," he said. "This involves digging through records and going door-to-door for additional information."

Indeed, he added, this old-fashioned genealogical detective work is being carried out by scientists who typically conduct their research in sterile lab environments, looking through microscopes. It is, Batzer explained, a necessary part of genetic research.

"The first step in trying to actually identify a disease gene is to identify families with these particular disorders and their relatives," he said.

So far, the combination of legwork and lab work has paid off. The researchers have identified the precise mutant gene that gives rise to Usher Syndrome. In fact, Batzer said, thanks to the good family and historical record keeping within the Acadian population, they were able to determine when the new mutation occurred.

Since this discovery, Batzer said, the researchers have been able to develop a test for the mutation that causes the Acadian form of Usher Syndrome, which, in turn, allows them to offer counseling to those who carry it.

Ultimately, he said, the hope is to develop an effective method of early intervention or treatment that corrects the abnormalities caused by the mutation.

In addition to his work on Usher Syndrome, Batzer and others in his Laboratory for Comparative Genomics at LSU are working to map the genetic "trail" of the Acadian population from Louisiana, back to Canada and Europe.

"We want to know where these people come from ancestrally," he said. "We know about their French-Canadian roots, but we're still trying to sort it all out. It's not as easy as you might think."

Batzer explained that the research becomes difficult because the genetic differences among Europeans are slight. Therefore, pinpointing exactly what part of Europe a particular family or group came from can take a great deal of painstaking research.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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