The Holes in Our Genomes

Over the past two years, scientists have made a surprising discovery about our DNA. Like a book with torn pages, duplicate chapters, or upside-down paragraphs, everyone's genome is riddled with large mistakes. These "copy number variations" can include deletions, duplications, and rearrangements of stretches of DNA ranging in size from one thousand to one million base pairs. New tools to screen for such mistakes, described this month in Nature Genetics, should generate a more complete picture of the genetic root of common diseases.

Over the past few years, advances in gene microarray technologies, which can quickly survey large volumes of DNA, have allowed scientists to screen more human genomes than ever before, resulting in a flood of information linking specific genes to disease. Most of these studies begin by looking for single-letter changes in the DNA code, called single-nucleotide polymorphisms, or SNPs (pronounced "snips").

Scientists have now adapted these microarrays to identify both small SNP changes and copy number variations, which they hope will help them identify a larger fraction of disease-causing genes. In one of the papers in Nature Genetics, David Altshuler, a physician and scientist at the Broad Institute, in Cambridge, MA, and his collaborators described the design of such a chip, in collaboration with genomics instrument maker Affymetrix, which they then used to map this kind of variation.

I just wrote about how the lack of testing for copy number variations was a serious problem for personal genome sequencer 23 and Me. Hopefully they will be able to integrate these new tests in their next release.

via Technology Review