Molecular biologist Xiangjun Liu wants to know whether something in your genes can predict your likelihood of contracting a debilitating disease. The human genome contains many small person-to-person variations called single-nucleotide polymorphisms (SNPs). SNPs are associated with a variety of diseases, but defining which combination of SNPs can predict the onset of a specific disease is a formidable task. As a researcher at Celera Genomics in Rockville, MD, Liu laid the groundwork for that effort by leading a team that sifted through billions of genetic sequences and produced a database of 2.8 million SNPs. Researchers worldwide are using these data to learn which genetic variations are involved in diseases and how those variations might affect drug efficacy and toxicity in different people. In February 2002 Liu returned to his native China to advance this work as director of Tsinghua University’s Bioinformatics Research Lab in Beijing. The lab is trying to pinpoint the SNPs associated with atherosclerosis and other ailments. Liu also heads a Chinese government project to analyze SNP findings worldwide. Ultimately, Liu hopes to identify people likely to develop a given disease, so doctors can work proactively to prescribe treatments that will prevent or minimize symptoms.