SUNDAY, May 22 (HealthDay News) -- The severity of cystic fibrosis, a life-threatening hereditary condition that affects the lungs and digestive system, seems to be influenced by genetic variations, researchers have found.
"Most cystic fibrosis patients born today live to their mid-30s, but that's an average. Some succumb to the disease before their 10th birthday, while others live into their 50s and we wanted to know why," Dr. Garry Cutting, a professor of pediatrics and member of the McKusick-Nathans Institute for Genetic Medicine at Johns Hopkins, said in a Hopkins news release.
The study, published online in Nature Genetics, used DNA from 3,467 patients -- including unrelated patients from the Genetic Modifier Study out of the University of North Carolina at Chapel Hill, the Canadian Consortium for Genetic Studies out of the University of Toronto, and related patients and their parents from the CF Twin and Sibling Study at Johns Hopkins.
The researchers hope their findings will help extend the life expectancy of people with the disease. "To achieve this goal, we had to work together as one group," Cutting said.
The investigators from all three studies collaborated and analyzed 600,000 sites of variation within the genome in search of common variations that are more frequently associated with severe cases of cystic fibrosis.
The result: The researchers were able to identify a region encompassed by two genes on chromosome 11 linked to severe cases of the disease. A second region on chromosome 20 was also identified. Continued study of this region revealed five genes that are turned on in respiratory cells, some of which are known to cause inflammation.
"We already know which gene causes cystic fibrosis, but to a large extent that gene does not by itself explain how severe the condition will be," explained Cutting. "Now we've discovered new genes that influence the course of disease and may enable prediction of disease severity and, most importantly, the customization of treatments for patients with unfavorable genetic modifiers -- this is the realization of individualized medicine," he added.
The investigators pointed out that further studies are needed to determine exactly how these genes alter the severity of cystic fibrosis.
"Of course we want to continue to push the median life expectancy up so that hopefully patients with more severe cases of cystic fibrosis will, with multimodal therapy, survive longer. And this is the first step toward developing such therapies for these patients," Cutting concluded.
The Cystic Fibrosis Foundation provides detailed information on the symptoms and treatment for cystic fibrosis.
-- Mary Elizabeth Dallas
SOURCE: Johns Hopkins Medicine, news release, May 22, 2011
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