The study examined DNA methylation — an “annotation” of DNA that alters gene expression without changing the genomic sequence itself — in a group of diverse Latino children. Methylation is one type of “epigenetic mark” that previous research has shown can be either inherited or altered by life experience. The researchers identified several hundred differences in methylation associated with either Mexican or Puerto Rican ethnicity, but discovered that only three-quarters of the epigenetic difference between the two ethnic subgroups could be accounted for by differences in the children’s genetic ancestry. The rest of the epigenetic differences, the authors suggest, may reflect a biological stamp made by the different experiences, practices, and environmental exposures distinct to the two ethnic subgroups.
Researchers and clinicians have known for many years that different racial and ethnic populations get diseases at different rates, respond differently to medications, and show very different results on standard clinical tests: “For a whole range of medical tests, whether your physician is told that your lab result is normal or abnormal depends entirely on the race/ethnicity box that you tick on an intake form,” Zaitlen said.
The researchers turned to epigenetics to search for answers to these questions because these molecular annotations of the genetic code have a unique position between genetic ancestry and environmental influence. Unlike the rest of the genome, which is only inherited from an individual’s parents (with random mutations here and there), methylation and other epigenetic annotations can be modified based on experience. These modifications influence when and where particular genes are expressed and appear to have significant impacts on disease risk, suggesting explanations for how environmental factors such as maternal smoking during pregnancy can influence a child’s risk of later health problems. Paper. (public access) – Joshua M Galanter et al., Differential methylation between ethnic sub-groups reflects the effect of genetic ancestry and environmental exposures. eLife, 2017; 6 DOI: 10.7554/eLife.20532 More.
With luck, epigenetics can thread the defile between “scientific” racism and unquantifiable claims about “environment.” From an epigenetic perspective, whether a person will be affected by a given problem may depend not so much on the genes inherited but on where their switches have been set in recent generations. And switches can be reset, after all.
See also: Epigenetics: How many methylation patterns can be attributed to ethnic ancestry?
Epigenetics becomes, increasingly, a normal study area in science
Epigenetic change: Lamarck, wake up, you’re wanted in the conference room!
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