Microarrays present researchers with something of a catch-22: In order to find something, you have to know what you're looking for. If you're looking for new functional elements, your microarray needs to contain probes designed to target them. With many transcribed regions, protein-binding sites, and even genes still missing from genome annotations, however, even so-called "whole-genome" arrays with millions of features are likely to miss critical sequences.
But that is changing, thanks to rapid advances in the density of probes that can be packed into a single chip. In recent years, interest in hitherto-unexplored regions of DNA derided as "junk" has spurred the development of a new class of microarrays called "tiling arrays," in which probes are not designed to target known genes or promoters, but simply laid down at regular intervals along the length of the genome.
"It's much more unbiased. if you tile across a whole genome or ...
