“It’s as if you’re looking down from an airplane, and you can’t tell the difference between a ten storey building and three storey building. You have to get closer.”

Dr. Stephen Scherer, a researcher at Toronto’s Hospital for Sick Children, is trying to describe the challenge of observing the incredibly small and complex world of genes.

A gene is one section of “rungs” on the spiraling, ladder-shaped DNA molecules we carry in the nucleus of every one of our cells. These sets of rungs form chemical patterns that carry directions for making the substances— mainly proteins—that our bodies need. There are as many as 30,000 genes in human DNA, and the ability to observe them is crucial to understanding how a healthy body operates, and what happens when things go wrong.

It’s impossible, however, to see the DNA “ladder” with a conventional microscope. While the strands of DNA in each of our cells measure an amazing 1.5 metres in length, the “rungs” are only one trillionth of a centimetre wide—and there are 3 billion of them.

To glimpse what’s going on at this impossibly small scale, scientists use a process called DNA microarray scanning. A microarray is a microscopic grid of chemically-generated DNA fragments, created using some of the same techniques used in making computer chips. When researchers introduce a sample of real DNA to the microarray, coloured dyes show how the sample reacts to the artificial fragments at various points on the grid. In this way, scientists can determine what genes are present in the sample, and what parts of those genes may be missing or modified.

The larger the number of points on the grid, the more detailed the information that can be retrieved from a single sample. To use Dr. Scherer’s analogy, they can fly lower and closer to the world of genes—and see more. The latest microarray scanners, including a new machine at the Hospital for Sick Children, offer grids containing a million DNA fragments. “That’s a hundred-fold increase in resolution over our previous devices,” says Dr. Scherer. “We can see deletions and changes that we couldn’t see two years ago.”

Dr. Scherer is using the technology, funded in part by an investment from the Ontario Innovation Trust, to probe the role genes play in autism. He predicts that this kind of genetic research will change our approach to the whole field of medicine. “Traditionally, a diagnosis is made by a doctor after giving you an exam or chemical test. But with genetic testing, we can, in some cases, diagnose a disease before it actually occurs—and take steps to prevent it.”