From the National Cancer Institute’s Science Writers’ Seminar, Gaithersburg, Md.
If you’ve read any medical literature or been to a medical meeting lately, chances are that you’ve heard of GWAS—genome-wide association studies. GWAS are hot and with good reason. Genetic studies of the past have been limited either to looking at linkages among related individuals or to the candidate gene approach, which directly tests the effects of genetic variants of a potentially contributing gene—already believed to play a role in a disease—in an association study.
With GWAS, researchers are now able to scan markers across the genomes of thousands of individuals and to identify genetic variation associated with a particular disease. The approach allows researchers to identify candidate genes that were previously unknown and may even occur in long stretches of noncoding—-or unexplored—regions of DNA. This approach has already been put to use in disorders as disparate as autism, type 2 diabetes, and inflammatory bowel disease. Just within oncology, GWAS have identifed 15 new candidate SNPs (single nucleotide polymorphisms) for prostate cancer, 12 for breast cancer, and 10 for colorectal cancer.
Researchers can barely contain their excitement with this amazing new tool. But—and you KNEW there was a but—it will be quite a while before the research translates to useful information for physicians and patients like improved risk models, screening tests, or novel targeted drugs. GWAS have to go through several iterations just to determine whether the initial candidate SNPs identifed are not merely statistical figments of the imagination. Then, once you have “real” candidate SNPs, what do you do with them? You have to figure out what they mean: Do they play a role in etiology or gene-environment/lifestyle interactions? Are there druggable targets? What, if any utlity is there for risk prediction?
Yes, GWAS hold great promise, but today they are just the begining of the begining.