epigenetics

Everything that your cells are capable of producing is recorded in your genetics, the arrangement of base pairs in the spiral-staircase-shaped molecule of your DNA. The sequence of those base pairs are step-by-step recipes for producing the molecules that your body needs to exist.   The DNA, however, is a junked up basement chock full of recipes. It includes some remnants of our entire evolutionary development for the last billion years or so. What makes the recipes useful and active, however, is another chemical signal that piggybacks onto the DNA molecule.

DNA doesn't exist by itself, you see.  It comes packaged with other chemicals that scientists are discovering will code for other useful information. The parts of your DNA library that are actually produced are marked differently by chemicals called methyl groups. These extra markers identify sections of DNA as being "heavy use" (easily pulled out for use by your cells) or "light use" (requiring more time and effort to unlock and use). So, for instance (and oversimplified), the cells in your heart are actively using only the muscle recipes while the cells in your brain are actively using only the neuron recipes. All of your cells have the same DNA, but they have different methylation patterns so they behave differently. Exposure to stressors can even activate some old sections of DNA, and leave them active for future use. Post-it notes for DNA... provided by methylation patterns attached to the DNA.

The DNA and these other markers is altogether called chromatin. Scientists have discovered that it's not just DNA information that is passed down along generations. The whole chromatin passes information from parent to child. So the environment and lifestyle of the parent shapes both the genetics (DNA) and the epigenetics (methylation) of the child.

Which brings me to today's news...

A team of McGill University scientists has discovered important differences between the brains of suicide victims and so-called normal brains. Although the genetic sequence was identical in the suicide and non-suicide brains, there were differences in their epigenetic marking – a chemical coating influenced by environmental factors.

It appears that humans abused as children can undergo epigenetic change. Their brains are functionally different. Moreover, since we keep finding evidence that epigenetic changes can be inherited, it could very well be true that the trauma will remain with the family line for generations after the initial incident. Mother Nature, she tries to keep future generations prepared for the hardships of previous generations. A different way of arguing "original sin", perhaps.

It is my personal theory that autism represents an epigenetic response to the current chemical environment (altered by modern human society). I claim that autistics are humans with an awakened genetic machinery from our recent (in evolutionary terms) past. There's still a lot of research to be done, but so far I think the results are already very promising.

My favorite epigenetic database is in New Zealand, the catalog of imprinted genes and related effects. I like their database because it's easy to search across species and for particular effects. Go ahead, search for autism. They have several curiosities identified already.
http://igc.otago.ac.nz/Search.html

PubMed talks about a new database under development called MethDB. I don't like its search features as well, but I suppose that can improve in the future. For general information, there's Epigenetics Station.  (*sing* Conjunction junction, what's your function?)

So there you have it, gentle students. A short introduction to the new science of epigenetics.  It's going to change a lot of our thinking about product safety.  What medicines or manufacturing chemicals have tested safe against genetics but may still alter our epigenetics?  Nobody knows.... yet.