Dr. Oefner has tried to find genes that let a simple yeast withstand high temperatures. But although it's far easier to track yeast genes than human genes, Dr. Oefner and his colleagues have struggled. Even there, we have tremendous difficulty really proving it. Another challenge in finding disease genes is that many disease symptoms are hard to measure precisely. Take blood pressure, Dr. Oefner said.
Blood pressure varies from day to day, and even within a given day.
If a gene affects blood pressure by only a few points, tracking the gene with SNPs may be impossible. To take full advantage of SNPs, scientists may have to come up with better ways of measuring the ups and downs of the human body. Still, the work with SNPs is a sign of great progress in genetics, Dr. Oefner said. Dr. Boerwinkle said connecting SNPs to disease might be more successful if scientists can develop different ways to gauge the severity of disease. It might be easier, he said, to connect SNPs directly to the kidney compounds than to the blood pressure.