Map of life expectancy at birth from Global Education Project.

Wednesday, May 31, 2006

You just might want to know about this . . .

If you think the corporate news media's Operation Ignore on the Clinton/Obama malpractice reform bill has been impressively successful, you'll really be impressed by this one. NIH is considering a large-scale ... excuse me, that would be humongous-scale project to collect genetic samples and longitudinal information on health (i.e., information that tracks individuals over many years) on hundreds of thousands of Americans. If you think about it -- which it appears no politicians or reporters are currently doing -- you will immediately realize that there are quite a few interesting questions associated with this proposal.

Accordingly, the Secretary's Advisory Committee on Genetics, Health and Society (SACGHS), established in 2002 to advise the Secretary of Health and Human Services, has prepared a draft report examining, well, at least some of these issues. I must say that the basic format of the report is to raise objections and then systematically answer them, the conclusion that the study should go forward being a priori. You can download the report -- a 57 page PDF -- from this page. The Executive Summary is not available as a separate download.

It's really not feasible to adequately summarize all of the issues in a blog post. Although the Committee says all the right things about the importance of public participation in decisions about such a study, I'm not sure there is an adequate answer. As they say, "[N]ew issues with strong scientific content sometimes seem particularly ill-suited to one-time techniques for soliciting opinion (e.g., a typical public opinion poll). Because most members of the public will be unfamiliar with the concepts of a large population project, concerted efforts must be made to educate, inform and solicit feedback and input."

That's not the only set of relevant concepts that most members of the public will be unfamiliar with. You can read SACGHS summary, which is too long to reproduce here. But here is my deeper background on this.

Many people -- including, sadly, quite a few who ought to be well informed -- have an inaccurate understanding of the relationship between genes and health. I don't know exactly how much each of my 5 1/2 readers knows about biology, so I'll probably insult some people's intelligence while baffling others, but what can you do? A single gene, in general, constitutes the instructions for making a single chemical called a peptide. Long ones are called proteins, and there are also shorter ones that carry messages within and between cells. That's an oversimplification because genes often code for long peptides that get cut apart to make various molecules. Genes are not only essential to producing the chemicals needed for biological functioning; by a complex dance between genes and messenger compounds that turn them on and off, the developmental process from fertilized egg to adult animal is coordinated. The activation and inactivation of genes continues during adulthood in the process of tissue maintenance and repair, which includes ongoing differentiation of cells from stem cell reservoirs; and in response to environmental cues and metabolic demands.

A common, fundamental error is to view genes in a highly reductionist, deterministic way. It is rarely accurate to say that a variation in a single gene is the cause of a disease. Some people would say it is never entirely accurate although I find that attitude tendentious. It is pragmatically justified to say that Cystic Fibrosis, Hutington's Disease, and some others are caused by specific genetic variations or "defects" if you will. However, development and healthy functioning in general are not determined by genes, but by interaction between genetic programs and the environment. The first environment is of course the womb, and then we live out in the world. Whether a particular genetic endowment predisposes to good health or disease depends on the context. A very important additional complication is that such predispositions are seldom traceable to single genes, but rather depend on complex interactions among multiple genes and the environment, such that teasing out all the strands is difficult, or even entirely unfeasible.

A widely cited example is that Native Americans in the United States have a 2 to 3-fold excess prevalence of Type 2 diabetes. One could say, then, that their genetic heritage places them at risk, and we could solve the problem by identifying the biochemical pathways between genes and disease, and intervening with the appropriate chemical correction. That conclusion would be objectionable, however, because prior to the European invasion, indigenous Americans never developed Type 2 diabetes; and the disease continues to be unknown among indigenous people who live in rural areas of Central and South America and pursue a traditional way of life. When those people move to cities, however, or to the United States, they become at high risk.

So, is the disease in their genes, or in society? Furthermore, what if we do the large population study and discover the combination of gene variants that predisposes to Type 2 diabetes. Do we do genetic tests in order to characterize people's risk of a disease such a Type 2 diabetes, and find that 90% of Navajo, 80% of immigrants from Central America, and 70% of immigrants from Mexico, have the risk profile? Do we charge them more for health insurance, discriminate against them in hiring? Do we do a second crash research program in order to develop the pharmaceutical intervention to correct for their genetic "defect," and then sell it for $3,000 for a yearly supply? Do we target intervention programs to try to get people of Native American heritage to maintain a healthy weight, consume high-fiber, low calorie diets and be physically active as their ancestors were? Or do we try to make fundamental changes in public education, food marketing, the built environment, recreational opportunities and transportation systems so that the entire population is at lower risk?

We can do the latter, even the latter two, without the proposed population study. The value of the study is in making the previous options possible. Is that a good investment of billions of dollars? What are the potential benefits and, yes, risks, of gaining such knowledge? How might the risks be ameliorated, the benefits enhanced? Or does it make more sense to spend the money on something else?

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