A new software tool allows scientists to link different human diseases and traits through the genetic variations they share. Credit: Liuyang Wang, Dennis Ko lab
A new study hints we should be paying attention to omega-6, omega-7 for improving/ worsening Crohn’s. Some research has suggested that omega-3 fatty acids can relieve inflammation. Research has suggested high-fat diets may be linked with Crohn’s disease, but never have the 2 been joined through shared genetics. Certain subtle genetic variations — as small as a single-letter change in the DNA — seem to occur more often in people with Crohn’s disease. Separate lines of work show that specific genetic variations are linked to higher levels of some fatty acids (molecular building blocks of fat) in the bloodstream.
In the new study, researchers identified genetic overlaps between palmitoleic acid, a type of omega-7 fatty acid, and Crohn’s with a software tool they call CPAG (“SEE-PAG”; short for Cross-Phenotype Analysis of GWAS). The software allowed them to compare the results of the more than 1,400 genome-wide association studies (GWAS) that have been published on the topic so far.
“The basis of the approach is simply to ask, ‘Is the [genetic] overlap between the two diseases or traits more than you’d expect just by chance?'” said Ko, Duke Center for Host-Microbial Interactions. The software, just like the genome-wide studies it mines, does not predict the relationship between one trait or disease and another, however.
To test whether fatty acid levels in the bloodstream was a cause or a consequence of disease, they used a zebrafish model of Crohn’s disease that had been developed by Stefan Oehlers. To the researchers’ surprise, it wasn’t omega-7 (palmitoleic acid) that significantly worsened inflammation but rather its saturated counterpart, palmitic acid, which is found in olive oil, butter, cheese, milk and meat.
Another unexpected finding was that an omega6 fatty acid (linoleic acid), which is present in vegetable oils, lessened inflammation in the fish. Omega-6 had been shown in a previous study to be lower than normal in the blood of people with Crohn’s.
Ko is quick to note that these new findings do not warrant radical dietary changes in people with Crohn’s: More studies, including more refined genetic analyses of fatty acids and Crohn’s and testing in animal models, are needed. “If we can deepen our understanding of lipid imbalance in Crohn’s disease and the consequences of having too much or too little of any one lipid in particular, then we might eventually be able to develop new strategies for managing Crohn’s disease and other inflammatory disorders,” said Rawls, an associate professor of molecular genetics and microbiology in the Duke School of Medicine. http://today.duke.edu/2015/09/crohns
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