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May 20, 2004
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Gene discovery offers look into health problems
Uncommon insight

Dr. Willie Davidson
Dr. Willie Davidson of Simon Fraser is partnering with MUN researchers.
By Sharon Gray
It’s a genetic disorder few have heard of, but the latest step in identifying one of the genes responsible for Bardet-Biedl Syndrome (BBS) could provide clues to health problems in the general population, including weight gain, diabetes, kidney disease, loss of vision, and learning difficulties.

It has taken the skills of a number of diverse research groups to successfully identify the genes responsible for this disorder, and Memorial University of Newfoundland’s contribution has been significant. In Newfoundland, research on BBS began in the 1980s. The syndrome, characterized by increased weight, extra fingers and toes, vision problems leading to blindness typically in the teens and a host of other health problems such as diabetes and kidney dysfunction, affects people around the world but it is more common in Newfoundland. The identification of the first gene linked to a complex disorder called Bardet-Biedl Syndrome was published in the September 2000 issue of the scientific journal Nature Genetics.

The research effort begun at Memorial has grown to an international team comprising investigators from Memorial, Simon Fraser University, Johns Hopkins and University College London. On May 14, 2004, the journal Cell published a paper on the discovery of another Bardet-Biedl Syndrome gene (BB55). The paper is titled Comparative Genomics Identifies a Conserved Flagellar and Basal Body Proteome that includes a Novel Gene for Bardet-Biedl Syndrome.

“It is truly an international story, but with very much a Memorial University and Simon Fraser University connection,” said Dr. Willie Davidson, formerly a faculty member in biochemistry at Memorial and now on faculty at SFU. “The family comes from Newfoundland and when I was still at Memorial we – Drs. Pat Parfrey, Jane Green, and then-graduate students Michael Woods, Terry-Lynn Young, and Lynnette Penney – discovered the genetic locus for BBS5, published in the American Journal of Human Genetics in 1999.”

Dr. Davidson said the team has been looking for the actual gene and the changes in the DNA that cause the disorder for about five years. “It was only thanks to a great bit of teamwork involving international collaborators from London, England, Johns Hopkins in Baltimore, University of Alabama at Birmingham, and Washington University in St. Louis that we were able to put it all together.”

Originally the research team at Memorial determined that there are several different BBS genes in different Newfoundland families and a collaboration was established with Baylor College of Medicine to identify the genes involved. The BBS gene first identified (BBB6) was the result of this international collaboration. “It was unexpected that there would be so many different genes causing this complex disorder,” said Dr. Jane Green, Genetics, Memorial. “This made it extremely challenging to identify a specific gene.”

Identification of BBS6 eluded researchers until the announcement of a gene responsible for McKusick-Kaufman Syndrome (MKKS), another rare disorder that shares some clinical features with BBS. Evidence was found that one of the BBS genes existed on chromosome 20 (BBS6) and mutations were identified in five Newfoundland and two European American families with a history of BBS.

Dr. Davidson said the paper published this month in Cell describes a variety of techniques and model organism studies that have produced a far better understanding of what is going wrong in BBS. “If we can understand BBS, then we may get a better handle on what causes one or more of the clinical aspects – obviously, obesity and diabetes would be important.”

Elizabeth Dicks, nurse-coordinator of the project at Memorial, said ongoing work on this genetic disorder involves a kin study. “We are starting to contact all relatives to do a phenotype-genotype study to see if carriers display some of the characteristics of BBS. It is a recessive disease which means someone with the syndrome must have mutations in both genes to get it. We want to find out if people who are carriers of one of the BBS genes have any clinical symptoms, such as increased risk for diabetes or hypertension.”

 


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