The genetic code is contained on DNA. From this DNA, RNA is made, very similar but a couple important differences. From this RNA, all of the proteins that make up our body are made.

Of all of the chronic smokers in the world, only about 10 percent develop serious emphysema (now called chronic obstructive pulmonary disease or COPD).

What we are looking for:

The genes that are responsible for causing those 10 percent to develop COPD.

How we (I) are looking for it:

We take blood from COPD patients when they are stable and when they are having a flare-up. I take the white blood cells (WBC's) from the blood and explode the white blood cells to extract the RNA from the cells. From the RNA I make DNA (a reverse process of what happens in our bodies). I take the DNA and make a bunch of copies of it. Then I put this DNA on a glass plate which has hundreds of gene markers on it. With the help of a couple computers, I look for genes that are up-regulated during the flare-ups as compared with the stable periods. These then are the likely genes that cause COPD.

Not as simple as this, but the idea is there. This is cutting-edge science.