An interaction between cigarette smoking and a susceptibility gene, called LOC387715, greatly increases the risk of developing age-related macular degeneration (AMD), Duke University Medical Center and Vanderbilt University Medical Center have found.
The combination of these factors accounts for as many as one third of the cases of AMD, the researchers estimated. The study represents one of the first examples of an interaction between genetic and environmental factors in the development of a common disease, they said.
The researchers said their findings emphasize the importance of genetic factors in the onset of AMD. They also said that the research has the potential to reduce the impact of the version, or allele, of the LOC387715 gene on the aging population by public health efforts, such as smoking prevention and cessation programs.
The results of the Duke research appears in the March 6, 2006 online edition of the American Journal of Human Genetics, to be published in print in the May issue of the journal.
"The most exciting aspect of this research is that it is the combination of the gene and smoking that really puts you at risk," said Margaret Pericak-Vance, Ph.D., director of the Duke Center for Human Genetics and senior author of the report. "We demonstrate, for the first time, that a gene variant coupled with a modifiable lifestyle factor such as cigarette smoking confers a significantly higher risk of AMD than either factor alone."
"Several environmental factors have been implicated in AMD," said Jonathan Haines, Ph.D., of Vanderbilt Center for Human Genetics Research, a co-author in the study. "The strongest effect comes from smoking, which is why we included it in this study. Another risk factor is family history, which led us to look for the genes involved."
"We found that the gene variant increases AMD risk even if a person does not smoke," said Silke Schmidt, Ph.D., first author of the study. "If the person does smoke and has a bad genotype, the risk increases dramatically. This suggests that gene carriers can reduce their AMD risk substantially by not smoking."
The joint effect of the two variants and smoking may be responsible for up to 61 percent of all cases of AMD, said the researchers. The finding might also give those at greatest risk for developing the condition a chance to undergo therapies or quit smoking to slow the progression of the disease, they said.
The discovery gives researchers a chance to further understand AMD, explained Pericak-Vance. The hope is that this information could ultimately lead to better treatments and prevention for those afflicted with the disease.
Adapted from the following source: Duke University Medical Center