Oct. 18, 2001 Vol . 22, No. 4
By Carol Thorbes
Gene mutations linked to an extremely rare disease may be more prevalent in healthy people and those with common diseases than first thought.
Simon Fraser University dean of science Willie Davidson is a member of a team of international biomedical experts that recently made the discovery while studying the genetic origins of Bardet-Biedl syndrome (BBS).
Diabetes, obesity, blindness and kidney dysfunction are common illnesses that characterize Bardet-Biedl syndrome, a complex, hereditary disease that affects one in 160,000 people worldwide.
Davidson says his group initially thought a BBS sufferer had to have inherited two bad copies (one from each parent) of one of potentially seven genes to fully develop the disease.
In a recent study, they discovered that the more likely scenario for BBS inheritance is two bad copies of one gene and one bad copy of another.
The finding is so important that the internationally esteemed journal Science has published it, along with a commissioned peer review of the study's significance.
"Science likely commissioned the review because there are few hereditary diseases that are known to bridge the gap between those caused by mutations in one gene and those attributed to the mutation of multiple genes. BBS fits that bill," explains Davidson.
In their joint Science review, three geneticists write it will "be of interest to know the frequency of BBS mutations in the population because a two-gene model for this disorder would predict a higher frequency of single-gene BBS mutations."
Davidson says he and his colleagues are investigating how mutations in three genes, known to cause BBS, trigger the disease's associated illnesses.
"It's possible that redundant genes fill in for mutant BBS genes in healthy people and that's why they don't develop the full blown disease. But risk factors associated with mutant BBS genes and malfunctioning redundant genes could cause BBS carriers to still develop BBS's associated illnesses, such as diabetes or obesity," offers Davidson.
The scientists reviewing the team's work for Science come to a similar conclusion.
The trio conclude that the team's findings indicate, "BBS is an excellent model not only for more common multifactorial diseases, but also for disorders where the mode of inheritance is complex."
Last September, Davidson and his colleagues from Newfoundland's Memorial University, Baylor College of Medicine, Houston, Texas and University College London, London, England isolated BBS6, the first mutant gene linked to BBS.
Scientists believe the gene is involved in protein folding.
The initial findings of Davidson's group were published in the scientific journal Nature Genetics.
Since the discovery of BBS6, another group of scientists has uncovered two more BBS related genes: BBS2, a protein of unknown function, and BBS4, a protein involved in sugar processing.
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