US researchers have managed to cram fragments of every human gene onto a single glass chip the size of a thumbnail, a development described as another step towards personalised medicine.
The 'microarray', unveiled by biotech firm Affymetrix last week, will help scientists study the activity of the estimated 35,000 different human genes. It can be used to find out which genes are 'switched on' in a particular tissue, for example a tumour sample. The announcements signal the end of a race between several biotech firms, which have all been working for some time to launch the first 'genome on a chip'. Previously, the entire set of human genes was available on two chips, rather than one. 'The idea of probing the human genome's expressed genes on a single chip is an exciting concept' said Larry Thompson of the US National Human Genome Research Institute (NHGRI). But he added that NHGRI was unable to comment further, until scientists had worked with the chip and observed its capabilities.
While the single genome chips will save researchers time, enabling them to look at thousand of different genes simultaneously, they are still costly. And, reports the New York Times, the change from two chips to one is more symbolic than revolutionary: 'You can do just as good science with two chips, it just costs you a little more' Roland Green, of rival firm NimbleGen, told the newspaper. It is thought that while the whole genome chips will be invaluable in research, gene chips for diagnostic use will be more specific. Once scientists find out which particular genes are associated with, for example, tumour aggressiveness, they will then make smaller and cheaper diagnostic chips containing just those genes, says Jeffrey Trent, of the Translational Genomics Research Institute.