Deeper into the genome

The next large-scale human genome project after HapMap should catalogue inherited variation in the general population that directly affects gene function, argues Richard Gibbs. The International HapMap Project has catalogued the patterns of more than 1 million single-base changes (known as single nucleotide polymorphisms, SNPs) in the genome sequences of 269 people drawn from four diverse human populations1. Most of these SNPs do not directly influence gene function, but the data provide valuable information about the overall pattern of chromosome organization and offer new tools for finding disease-causing genes in humans.