Sunday, February 15, 2009

Epigenetic change during pregnancy

Regular readers of this blog will know that I have commented on epigenetic change before. Epigenetics is rapidly emerging as a significant contributor to our understanding of the ways in which our genes influence both behavior and disease.

Briefly, epigenetic changes to genes do not result in mutations, alterations in the gene sequence, but they do result in changes in the way a gene is translated into protein. In other words, epigenetic changes alter the phenotype (observed characteristic) of the person without changing the genotype (the actual gene they carry).

In a paper out this week researchers from the University of Cincinnati reported that children with in utero exposure to polycyclic aromatic hydrocarbons (PAH – common car pollutants) were more likely to develop early onset asthma (by age 5) and this was linked to epigenetic change in a gene associated with the development of asthma (ACSL3). Living in urban environments has always had certain risks associated with it, but as the earth’s population continues to immigrate into urban centers, we must attempt to anticipate the genetic and epigenetic changes that will result.

Since it was first described, epigenetic change has fascinated me. Certainly its association with disease is important, but even more interesting is its association with behavior. Can exposure to environmental stimulus modify behavioral norms? The early answer appears to be yes, but time will tell. Since exposure to pollutants can affect later disease in children, one wonders whether other behavior in pregnant women can affect disease and behavioral outcomes in their children. In addition, we now believe that epigenetic can be passed on to offspring – do the choices (whether chemical or behavioral) of either parent affect children in epigenetic ways that go beyond and yet reinforce decisions about child-rearing. Perhaps so…

These are profoundly interesting questions both on the personal level and on the level of community and the human race as a whole. One wonders what affect increased urbanization will have on the very structure of the human DNA. Are certain behavioral norms that are more common in cities than in rural communities being reinforced at the epigenetic level? If they are, will these traits become ever more engrained in the fabric of what it is to be human? Then, what affect will new behavioral norms have on our understanding of religious doctrines as expressed through the centuries of church tradition? Is there a genetic underpinning for what many have called the loosening of behavioral standards in some Christian traditions? Though we cannot prove it (yet), the idea is thought provoking.

Friday, February 6, 2009

Want your sequence?

New Scientist is reporting today that the cost of a complete genome sequence has dropped to a mere $5000. This announcement will lead to profound breakthroughs in genetics research - particularly in our understanding of the SNP's genomics scientists say will be necessary for use to design personalized therapies.

We will be able to know - for a relatively modest cost - the exact DNA sequences for thousands of disorders and diseases. Perhaps we will finally be able to understand the contribution of genetics to complex human behaviors.

In addition to complete genomic sequences, at least three more breakthroughs are necessary before we can take full advantage of our genetics:
  1. A computational breakthrough that can not only map the differences between genomes with billions of letters, but also cull out the significant differences in the coding sequences.
  2. A way to map epigenetic modification in genome-wide analysis. Carrying a gene is not enough, it must be expressed to contribute to a person's phenotype.
  3. A database of human disease that contains what is now considered to be private information for comparison to genetic information.
When mapping technology gets down into the $100's of dollars range, look for a push for large scale enrollment in a genetic disease database.