Scientists have found that culture may be leaving a heritable print on DNA. Separate from an ethnic group's genetic ancestry, these epigenetic signatures reflect a group's shared environment and practices, and could play an import role in health and disease.
“These data suggest that the interplay between race and ethnicity as social constructs and genetic ancestry as a biological construct is more complex than we had realized,” said Noah Zaitlen, co-senior author on the new study, published in eLife. “In a medical context, both elements may provide valuable information.”
Think of it this way: While in general, every cell in your body starts off with exactly the same DNA, different tissues in the body switch some sections off and others on, depending on their role. For example, heart cells may have the information for how skin cells function but don’t need this, so they don’t follow these instructions, and vice versa. This is, in part at least, controlled by the epigenetics, or methyl groups that attach to certain regions of the DNA in each cell type.
In a similar way, certain events or environments can, in turn, do a similar thing. For example, smoking is known to alter how and where methyl groups attach to DNA, changing gene expression. A study a few years back claimed that the extreme stress experienced by Holocaust survivors also left markers in their DNA, markers that were then passed down to their relatives. This latest study reports that they have found that these experiences, practices, and environments in different ethnics groups may also be leaving a print in people’s DNA, and could be contributing to their health risks.
Different ethnicities are known to suffer from different health problems at differing rates. Diabetes, for example, is twice as prevalent among Hispanics than non-Hispanic Caucasians in America, while Crohn’s disease is more common in Europeans. “A lot of our research involves trying to tease apart how much of health differences between populations are genetic and how much are environmental,” said Zaitlen.
To examine these influences, they turned to epigenetics, due to its unique position somewhere between genetic ancestry and environmental influence. By looking at the methylation signatures of 573 children from Mexican and Puerto-Rican descent, out of 916 epigenetic sites that varied with ethnic identity, they found 205 that could not be explained through their ancestry.
Many of these corresponded with methylation sites already identified by previous studies as sensitive to influences from environmental factors, such as exposure to maternal smoking or diesel exhaust fumes. The researchers therefore suggest that the common backgrounds of people from certain ethnic groups may be impacting their genes, and as a knock-on effect, impacting their health.