[VIEWPOINT]Unraveling the body's workings

More and more people are dreaming of a rosy future when the Human Genome Project is completed. Because God's design of the human body is coming to light in detail, people are anticipating tailored human beings, perpetual youth and longevity and overcoming cancer and other diseases. But life's phenomena are not that simple. Some genes that cause incurable diseases, such as cystic fibrosis and muscular dystrophy, are already known. But even if we substitute some good genes for faulty ones, it will not mean that all diseases can be cured. Most incurable diseases are related not to a single gene but to hundreds of genes in combination.

Scientists have estimated the number of human genes at 50,000 to 100,000. But through the Human Genome Project, we have classified only 35,000 genes. Tens of millions of life's phenomena in the human body, such as metabolism and the outbreak of diseases are caused by the interaction of genes. That should be an alarm bell for those who have the belief that genes are everything.

Identical twins are a good example. The possibility that the twins would get a disease simultaneously is 20 to 50 percent. Even though their genes are 100 percent identical, a twin can get a disease while the other stays healthy. There are differences in interactions acquired in the course of one's lifetime.

In biotechnology, we have to keep an eye on the interaction of genes in the human body as a whole, and a new science called physiome is coming to the fore. Unlike genome research, it emphasizes the interactions and functions of components of the human body rather than the structure.

Thanks to the Human Ge-nome Project, the sequence of 3 billion base pairs, or basic components of genes, has come to light in detail. But we still do not know what specific base pairs do in concrete terms. Physiome can solve this problem.

Physiome utilizes information technology to examine the "woods" of life's phenomena. Through simulations we can assess tens of thousands of possibilities. The genome is a microconcept that digs out genes and the molecules they are made of, but physiome is a macroconcept that looks into life phenomena by coordinating information and biological technology.

The U.S. Food and Drug Administration in 1997 suspended its approval of Mibefradil, a hypertension medicine made by the multinational pharmaceutical maker Hoffman LaRoche because of side effects on the heart. The FDA demanded that the firm should meet safety requirements through clinical trials on 1,000 hypertensive subjects. But Hoffman LaRoche did clinical trials on only 100 patients; the other 900 cases were simulated through an imaginary heart with the help of physiome theory. The company finally got approval and saved time and money that would have been needed for 900 clinical trials. From an ethical view of point, physiome is better because it did not raise risks of side effects in human patients.

Physiome can be a breakthrough in biotechnology, which has stalled with the conclusion of the Human Genome Project. Physiome studies on imaginary organs and tissues are already in progress. The International Union of Physiological Science is a principal center of the studies. Keio University in Japan and the U.S. National Institute of Health are making imaginary cells and a number of biotechnology start-ups are jumping into physiome study.

Life phenomena cannot be fully explained only by physics and chemistry principles. Genome study, an offspring of physics and chemistry, cannot unravel the complicated mystery of life by itself.

We need to be more humble in front of profound life phenomena. Even though physiome cannot clarify the substance of life perfectly, it can help us to know the workings of substances very nearly correctly through information technology and biotechnology. We are still not familiar with the term, but physiome deserves to be focused on as a next-generation field in this post-genome era.

* The writer is a professor of medicine at Seoul National University.

by Earm Yung-e