HUMAN GENOME PROJECT

also called Human Genome Initiative, scientific research effort to analyze the DNA of human beings and of several lower types of organisms. The project began in the United States in 1990 under the sponsorship of the U.S. Department of Energy and the National Institutes of Health and was scheduled to be completed in 15 years. Related programs were begun in several other countries in coordination with the American program. The project's ultimate goal is to identify the chromosomal location of every human gene and to determine each gene's precise chemical structure in order to elucidate its function in health and disease. Every cell of an organism has a set of chromosomes containing the heritable genetic material that directs its developmenti.e., its genome. The genetic material of chromosomes is DNA. Each of the paired strands of the DNA molecule is a linear array of subunits called nucleotides, or bases, of which there are four typesadenine, cytosine, thymine, and guanine. Genes are discrete stretches of nucleotides that carry the information the cell uses to construct proteins. The human genome is composed of about 3 billion base pairs and contains 50,000 to 100,000 genes. The genes take up only about 5 to 10 percent of the DNA; some of the remaining DNA, which does not code for proteins, may regulate whether or not proteins are made, but the function of most of it is unknown. The main goal of the Human Genome Project is to map the location of all the genes on every chromosome and to determine the precise sequence of nucleotides of the entire genome. Two types of maps are being constructed: genetic linkage maps and physical maps. A genetic linkage map provides the relative location of genes and other markers on the basis of how frequently genes are inherited together; the closer genes are to each other on a chromosome, the more likely they are to be inherited together. Physical maps locate genes in relation to the presence of known nucleotide sequences that act as landmarks along the length of a chromosome. One such marker used to map the human genome is a sequence-tagged site, a short sequence of nucleotides that occurs only once throughout the genome. A relatively detailed physical map is needed before sequencing can begin. Sequencing, in which the precise order of the nucleotide sequence is determined, is the most technically challenging part of the project. Making improvements in methods of sequencing and in data collection and interpretation are other goals of the project necessary for the 15-year deadline to be met. Similar studies were planned on the DNA of the laboratory mouse (Mus musculus), the nematode worm Caenorhabditis elegans, the fruit fly (Drosophila melanogaster), the yeast Saccharomyces cerevisiae, and the bacterium Escherichia coli. The rationale for this effort is that many genes with similar functions in disparate organisms have been conserved in evolution and show surprising similiarities. Genes from simpler organisms can thus be used to study their counterparts found in human beings. Another objective of the project is to address the ethical, legal, and social implications of the information obtained. Society will derive the greatest benefit from this knowledge only if it takes measures to prevent abuses, such as invasions of the privacy of an individual's genetic background by employers, insurers, or government agencies or discrimination based on genetic grounds. Human genome projects undertaken concurrently in Japan, the United Kingdom, Italy, France, and Russia are coordinated with the American effort through the Human Genome Organization, whose members include scientists from throughout the world. The potential utility of the Human Genome Project is immense. The information gathered will serve as the basic reference for research in human biology and medicine and will provide fundamental insights into the genetic basis of human disease. The new technologies developed in the course of the project will be applicable in numerous other fields of biomedical endeavour.