| CORP. FOCUS |
uses mass spectrometric methods to study SNPs. "The advantage of using a mass spectrometer as a detector is that the mass spectrometer is a self-validating instrument. If the assay works the first time you run it, you basically know that it works and know that it's valid," says Charles R. Cantor, Sequenom's chief scientific officer. Cantor was one of the driving forces at the Department of Energy behind the human genome project. Sequenom's scientists are interested in changes in the frequency of SNPs as the population ages. "We take advantage of the fact that most human diseases are late-onset. Age is a major risk factor," Cantor says. "If young people are carrying a harmful variation, they're still well, whereas an old person carrying that same variation has a very high chance that he's been made sick or killed by it. You make the prediction that variations that are harmful to health should decline in frequency as a function of age in the healthy population." So, Sequenom designs assays to look for every public-domain SNP in people's DNA, Cantor says. Each assay is specific for a single SNP. "We have a database of 1.7 million designed assays. Of those, we've run about 50,000 public-domain SNPs, and we've run another 50,000 private-domain SNPs, in terms of actual physical assays that have been performed in collaboration with Incyte, one of our partners," he says. Sequenom's assays work on the first pass 94% of the time. "We throw away the ones that fail. With these numbers, it isn't even worth looking at them again." The first 10,000 assays were performed in a collaboration with the National Cancer Institute, and the results were published earlier this year [Proc. Natl. Acad. Sci. USA, 98, 581 (2001)]. One percent of genes appears to show an age-dependent frequency in SNPs, Cantor says. He suspects that only 200 to 400 genes will be involved in disorders that affect a major population. Finding these genes in healthy people, however, gives no indication of what the diseases actually are. "After we find them in the healthy population, we have to go back and look at biochemically stratified populations or clinically stratified populations," he explains. "The advantage is that instead of having to do all the genes with these tricky populations, we only have to do 200 to 400. We can pay a lot more attention to the details." |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |