Genetic testing provides few easy answers

Courtesy of WSJ

If scientists could use one gene — or even a combination of five or 10 — to predict a person’s likelihood of developing a certain type of cancer, there might be fast progress toward developing drugs and finding other ways to help people avoid the disease. But some genetics experts are saying it may take a combination of hundreds of genes to make clear predictions. “With only a few exceptions, what the genomics companies are doing right now is recreational genomics,” Duke University geneticist David Goldstein told the New York Times. “The information has little or in many cases no clinical relevance.”

Goldstein was one of three writers of three commentaries on the issue in the current New England Journal of Medicine. Here are quotes from each:

Common Genetic Variation and Human Traits,: If effect sizes [of particular genes] were so small as to require a large chunk of the genome to explain the genetic component of a disorder, then no guidance would be provided: in pointing at everything, genetics would point at nothing.

Genetic Risk Prediction — Are We There Yet?: The availability of highly predictive and reasonably affordable tests of genetic predisposition to important diseases would have major clinical, social, and economic ramifications. But the great majority of the newly identified risk-marker alleles confer very small relative risks … Even when alleles that are associated with a modest increase in risk are combined, they generally have low discriminatory and predictive ability.

Genomewide Association Studies — Illuminating Biologic Pathways: Ultimately, the usefulness of genetic information for prediction will depend not on the absolute fraction of heritability explained but rather on how much this additional information can shift the cost–benefit ratios of available clinical interventions. For diseases without potential therapies, even perfect prediction might not be clinically useful. By contrast, for diseases with effective preventive measures that are too costly or for which the risk–benefit balance is nearly neutral, small increments in predictive power could help effectively target preventive efforts, with substantial clinical impact. As we’ve noted before, plenty of genetic experts believe predictive gene-based tests aren’t ready for wide use. Even genome guru Craig Venter has expressed skepticism about the relevance of any given variant.

Steve - do not waste your $ on the genetic lifestyle kits. What we DO know right now is that managing epigenetic pathways so as to not express genes negatively is sound science. Diet, lifestyle, and nutrients can calm those epigenetic pathways. How exciting!