A Primer on Microarrays

Your DNA is responsible for how your body grows and develops—as well as how susceptible you are to certain diseases. The human genome is highly complex, though, as are the ways in which mutations can occur and manifest. Fortunately, DNA microarrays provide a potent tool for study and diagnosis, both among large populations and within single subjects. Today, it’s possible to use microarrays to assess health risks, identify genetic disorders and more.

How Microarrays Work

A microarray is a collection of synthetic, single-stranded DNA fragments, comprising a known gene sequence, printed onto a microscope slide. DNA samples—one control and one experimental—are dyed and introduced to the microarray; these samples bind with the printed sequence where the respective nucleotide pairs complement each other. After weakly bound or unbound DNA sequences are washed away, what remains is a record of how closely the samples match the known sequence.

Applications of Microarrays

Microarrays allow for relatively easy comparisons between experimental or patient DNA samples and “typical” or healthy versions of DNA sequences. Early microarray experiments in the 1990s compared how genes were expressed in normal and cancerous cells to provide insight on how mutations gave rise to tumors or other abnormal cell growth. As research on gene expressions continued and the technology developed further, microarrays expanded in potential use, including application as diagnostic tools for individualized medical care, assessing how cell cultures respond to treatments or even performing genome-wide association studies to find links between variations across the human genome and particular possible diseases.

The Microarray Industry

With DNA synthesis becoming easier and less expensive, obtaining a custom microarray for use in diagnostics or research projects is now possible. The samples used can range in scale from a select few genes to entire chromosomal microarrays, and various methods of profiling can account for different types of mutation ranging from point mutations of nucleotides to large-scale duplication or deletion of chromosomal regions.