The recently initiated human genome project is a large international effort to elucidate the genetic architecture of the genomes of man and several model organisms. The initial phases of this endeavor involve the establishment of rough blueprints (maps) of the genetic landscape of these genomes, with the long-term goal of determining their precise nucleotide sequences and identifying the genes. The knowledge gained by these studies will provide a vital tool for the study of many biologic processes and will have a profound impact on clinical medicine.