Yesterday my dear sweet Man With Fins told me a hilarious story about someone who proposed to write a science column for the local newspaper that he edits. The lead for one of the columns read "Hardly a day goes by without thinking about DNA..."
I doubt that's true even for geneticists, so we collectively laughed uproariously.
Ironically, today I realized that I really had been thinking about DNA for the last couple of days because of a short article I read in The Economist about epigenetic imprinting. In short, mice that are licked and groomed by their mothers early in life grow up to handle stress better because that early experience adds a little chemical to a portion of their DNA which then changes the way that gene works. So, you could have identical genes expressed differently in two different people because they have different life experiences. The article paints a much more interesting picture of this. I certainly recommend reading it!
Among other things, epigenetic imprinting has been hypothesized to play a role in cancer and mental illness.
October is Breast Cancer Awareness month. This morning I heard a statistic that 90% of women who get breast cancer have no family history of it. I've also heard that aluminum in anti-perspirant has been linked to breast cancer, BUT did you know that epigentic imprinting may play a role in breast cancer and your weight at birth might be a risk factor?
A paper released this month in the International Journal of Cancer proposes that premenopausal breast cancer may originate in utero. That's right ladies - before you were even born your cells might have been marked. A higher weight at birth increases a girl's chances of getting breast cancer. "Loss of imprinting of growth hormone genes relevant for intrauterine growth, such as insulin-like growth factor 2 (IGF2), leads to abnormally high levels of these hormones evidenced by high birthweight," the study says.
I wonder how gestational diabetes plays into this. Women with gestational diabetes are at risk for having a baby that grows too large. Perhaps too much glucose causes the baby's genes to fail to turn off the growth factor?
I drink a lot of soy milk so I read this other abstract that says agoutis (cute rodents that can be seen in Belize and Guatemala where I saw them) not only change their hair color in response to ingesting phytoestrogen that is present in soy, but also receive protection from developing obesity by, you guessed it, the way the phytoestrogen changes how their DNA gets expressed. What's also interesting is that they say phytoestrogen is linked to "diminished female reproductive performance." Does that mean I harm my fertility by drinking soymilk?
More interesting genomic imprinting information can be found at geneimprint, a site set up by Randy Jirtle, an epigeneticist.