Human Genome Project Health Article

HUMAN GENOME PROJECT

The Human Genome Project (HGP) is an international research program that aims to spell out the complete genetic inheritance of human beings and selected experimental animals. The HGP's goal is to decode the complete DNA inheritance, or genome, of human beings by 2003; following completion of a draft in 2000 that charted 90 percent of the human DNA inheritance. In addition to decoding human and animal DNA, the HGP trains scientists, develops techniques for analyzing genomes, and examines the ethical, legal, and social implications of human genetics research.

DNA is the long thread of a molecule that carries genes. Each strand of DNA, packaged as a chromosome, bears thousands of genes. Each gene contains the instructions for making a single component of the body, usually a protein. The hereditary instructions embedded in DNA are written with a four-letter alphabet (A, G, C, and T). A single misspelling in the DNA code can lead to the production of a defective protein, which can cause disease.

Understanding the human genome, the complete set of genes, sheds light on how the human body works at the fundamental level of molecules. Genes orchestrate the many fantastic and elegant features of life, like the development of embryos, while variations in gene sequence influence each person's susceptibility to diseases, including common illnesses like cancer and heart disease. The HGP will ultimately answer a wide range of scientific and medical questions, including: How do cells work? How do complex organisms develop from single cells? How are living beings related to each other? How do diseases arise?

The HGP was officially launched in 1990, as a joint project of the U.S. government and international partners. It was established as a large-scale, coordinated research project, marshaling the collaborative effort of hundreds of researchers. Between 1990 and 2003, the HGP is expected to reveal the sequence of approximately 3 billion "letters" that make up human DNA to identify all of the approximately 100,000 genes in human DNA, and to make all this information accessible to anyone with access to the Internet. The tools the HGP has built, including increasingly detailed maps of the human genome, helped genetic researchers navigate the genome and discover scores of disease genes in the 1990s. By 2003, a 99.99 percent– accurate listing of the letters that make up the DNA in all the human chromosomes is expected; that readout of the human genome, along with catalogs showing how DNA sequences vary among individuals, will help scientists tease out the genetic basis for complex diseases like diabetes, Alzheimer's disease, cancer, and heart disease— illnesses whose origins can be traced to the effects of multiple genes, as well as social and environmental factors.

By helping reveal the molecular foundations of disease, the HGP is expected by some to transform health care. Genetic technologies are becoming increasingly available. For example, genetic tests are being used to confirm diagnoses for some conditions, and to help define prognoses. Other tests predict the risk for future health problems. In time, more detailed understanding of the molecules involved in disease is expected to promote more rational drug design, making for increasingly precise, in some cases individualized, pharmacologic therapies that will minimize side effects or even avoid them altogether. Ultimately, understanding the molecular origins of disease may reveal ways of preventing many diseases entirely, perhaps by circumventing molecular glitches that can lead to illness or by repairing the altered molecules outright.

While genetic information and technology are likely to create great opportunities for promoting health and preventing disease, some risks are likely to accompany these powerful technologies. Genetic information can be misinterpreted or misused. As knowledge about individuals' genetic backgrounds becomes increasingly widespread, some insurers and employers may use predictions about future health to limit or deny access to health care or employment. Therefore, protecting the privacy of genetic information and preventing genetic discrimination will be crucial. To tap the full benefits of genetics, the medical profession and the public will need to become better equipped to evaluate the meaning of genetic information and to make decisions about the use of the new genetic technologies. At the same time, proper oversight will be necessary to ensure that gene tests and technologies are valid and reliable, sensitive, and specific, and used in appropriate situations.

Genetics, which was largely confined to research laboratories during the twentieth century, is expected to pervade everyday life in the twenty-first century. In the arena of public health, it may be used to access individuals' risks for health problems and to develop programs of preventive health care. Knowing their susceptibility to various health risks, individuals may be able to adopt a schedule of surveillance, perhaps take medications that will prevent health problems, and ideally become motivated to adopt lifestyle measures that will minimize their risks.

Most observers argue that the goal of public health genetics programs should be phenotypic prevention—preventing the emergence of disease—rather than genotypic prevention which is trying to change the genes people inherit. To attempt to prevent the transmission of particular genetic traits to future generations as a public health measure would tread into eugenic territory. Instead, public health goals should be designed to forestall the clinical manifestations of genetic risks.

FRANCIS S. COLLINS

KARIN JEGALIAN

(SEE ALSO: Genes; Genetic Disorders; Genetics and Health; Medical Genetics)