The Human Genome Project (HGP) was a massive attempt to sequence the entire human genome, some 3.3 billion base pairs spread over 23 pairs of chromosomes. This project, started formally in 1990, was a worldwide effort driven forward by two groups. One is a private company called Celera Genomics, and its preliminary results were published in Science in February 2001. The other is a publicly funded group of researchers called the International Human Genome Sequencing Consortium. Their preliminary results were published in Nature in February 2001. Researchers were surprised to find only about 30,000 genes in the human genome. This figure has since dwindled to fewer than 25,000. This is similar to many other eukaryotes, including some as simple as the roundworm Caenorhabditis elegans.
What does one do with the information? From this information, we will eventually be able to identify all human genes and to determine which sets of genes are likely to be involved in all human genetic traits, including diseases that have a genetic basis. There is an elaborate interplay of genes, so it may never be possible to say that a defect in a given gene will ensure that the individual will develop a particular disease. Nevertheless, some forms of genetic screening will certainly become a routine part of medical testing in the future. It would be beneficial, for example, if someone more susceptible to heart disease than the average person were to have this information at an early age. This person could then decide on some minor adjustments in lifestyle and diet that might make heart disease much less likely to develop.
Many people are concerned that the availability of genetic information could lead to genetic discrimination. For that reason, HGP is a rare example of a scientific project in which definite percentages of financial support and research effort have been devoted to the ethical, legal, and social implications (ELSI) of the research. The question is often posed in this form: Who has a right to know your genetic information? You? Your doctor? Your potential spouse or employer? An insurance company? These questions are not trivial, but they have not yet been answered definitively. The 1997 movie Gattaca depicted a society in which one’s social and economic classes are established at birth based on one’s genome. Many citizens have expressed concern that genetic screening would lead to a new type of prejudice and bigotry aimed against “genetically challenged” people. Many people have suggested that there is no point in screening for potentially disastrous genes if there is no meaningful therapy for the disease they may “cause.” However, couples often want to know in advance if they are likely to pass on a potentially lethal disease to their children.
Two specific examples are pertinent here:
1. There is no advantage in testing for the breast cancer gene if a woman is not in a family at high risk for the disease. The presence of a “normal” gene in such a low-risk individual tells nothing about whether a mutation might occur in the future. The risk of breast cancer is not changed if a low-risk person has the normal gene, so mammograms and monthly self- examination are in order.
2. The presence of a gene has not always predicted the development of the disease. Some individuals who have been shown to be carriers of the gene for Huntington’s disease have lived to old age without developing the disease. Some males who are functionally sterile have been found to have cystic fibrosis, which carries a side effect of sterility due to the improper chloride-channel function that is a feature of that disease. They learn this when they go to a clinic to assess the nature of their fertility problem, even though they may never have shown true symptoms of the disease as a child, other than perhaps a high occurrence of respiratory ailments.
The nature of commercial enterprises coming up with genetic tests has become very controversial in recent years. For example, deCODE Genetics, a company in Iceland, released a breast cancer screen that checked for seven different base changes (called singlenucleotide polymorphisms, or SNPs). The price tag is $1625. Many scientists balked at the price, and many questioned whether the test is worth it. So much is still unknown about breast cancer that it is not clear whether knowing that a person has one or even all seven of the SNPs would be useful information, as it would indicate only a small percentage change in the chance of getting the disease.
Since the Human Genome Project was finished a decade ago, scientists have been eager to sequence other genomes to compare with human DNA. Such studies could show conserved sequences and shed a light on those genes that are key to the survival of similar biological species, as well as those that indicate changes that have occurred during the evolutionary process. Therefore, five years ago the National Human Genome Research Institute (NHGRI) assembled a list of 32 mammals and 24 other vertebrates whose DNA they would like to analyze. At an international symposium of geneticists, they determined that freezers around the world already contained DNA samples from over 16,000 different species. Shortly thereafter they launched the Genome 10K Project, which proposes to sequence 10,000 genomes in the next five years. Many feel that is wishful thinking, given that it means analyzing a genome per day. Also, to make it happen, the technology has to keep improving and getting cheaper. However, those involved are confident that the genomes can all be analyzed, although when is still in question.
Your genome could appear on an ID information could lead to genetic discrimination. For that reason, card in the foreseeable future.
Đinh Phong Sơn
