By Erin Brodwin From Business Insider

This week, a team of scientists used the genetic data on thousands of Icelanders to find out where some of our most troubling diseases come from.

They discovered that a condition called early-onset atrial fibrillation, a kind of irregular heartbeat, was closely linked to a single tweak in a particular gene called HYL4. All eight people in the study who had the mutation had the disease.

Alzheimer’s, on the other hand, is about twice as likely to develop in people with a change in another gene called ABCA7. (We still can’t tell exactly how the particular genetic tweak goes on to cause Alzheimer’s, but just spotting it is pretty groundbreaking.)

To figure all this out, the researchers used a method that’s basically the reverse of the way scientists have approached genetic data for decades.

And it could be the shape of things to come.

Genes to illness, rather than illness to genes
Traditionally, scientists take a group of patients who have a certain disease — like cystic fibrosis, for example — and then comb through their genetic data for commonalities that may (or may not) affect the disease. This time, the researchers looked at all their volunteers’ genetic data, picked out the ones with strange tweaks (or “mutations”), and then looked to see whether these people had any illness or disease.

“This approach completely turns the tables,” Icelandic neurologist Kari Stefansson, who founded deCODE, the company in charge of the research, said on a call with reporters.

In addition to helping them pinpoint a cause of atrial fibrillation and reveal a risk factor for Alzheimer’s, the scientists’ method helped them spot or confirm several other genetic changes that raise the risk of diabetes, heart disease, and gallstones.

Knocked-out genes
They also got a closer look at another type of mutation that shuts down a gene completely.

For decades, scientists have been deliberately shutting off genes in mice to better understand which ones do what and why. They call these turned-off genes “knockouts.”

Knockouts occur naturally too, of course, and not just in mice. In the Icelandic population in the new study, nearly 8% of people had a knockout.

So, rather than creating knockouts in lab animals and then studying what happens to them in the lab, the new research aims to spot the ones that are already present in people, and then see how these knockouts affect them.

Once the researchers start to learn more about the function of each of our genes, they can help pinpoint the roots of more genetic diseases — potentially paving the way for better drugs and treatments.

For more on this story go to: http://www.businessinsider.com/iceland-decode-research-holds-clues-to-genetic-disease-2015-3#ixzz3VpYtBXaa