African or European Ancestry: Immune System Adaptation Determiners

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African or European Ancestry: Immune System Adaptation Determiners

Human immune system fighting off infections defending and protecting the body from infectious diseases / Photo by monofaction via Shutterstock


Scientists have just identified a legitimate, genetic disparity between peoples of African and European descent, and it’s a difference that determines how one’s immune system causes inflammation. The research team that published these findings in PLoS think the disparity they’ve found stems from the evolution of the immune system in humans as well as the pressures that malaria inflicted on the African immune systems for such a long stretch of human history. The fact that they can even pontificate along those lines, though, speaks to just how much the general public doesn’t know about how ancestry works, which is fascinating for many in an age when one of the most increasingly lucrative services in medical science is that of tracing one’s ancestry.

The immune system of the human body evolved in such a way for thousands of years that it was becoming more and more efficient at fighting off all sorts of infections, so its responses to bugs became tailored to bugs typical of certain local regions. Modern hygiene has yielded far fewer attacks on the immune system, but there are ancestral differences that illustrate how the major threats have shaped the human immune system. In order to comprehend how this is so, a group of scientists put molecular, genetic and epidemiological data together, pooling it all from 855 people of European descent and 914 people of African ancestry. The data came from the African-American Breast Cancer Epidemiology and Risk (AMBER) Consortium.

They analyzed blood samples to find 14 separate chemical transmitters involved in the inflammation process, and they found notable contrasts between peoples for exactly half of them. Lifestyle factors like obesity, age, smoking, level of education, and alcohol use were all found to be potential explanations for these differences, but the team also noted a genetic variant that manifested in those of African ancestry. That variant directly regulated two of the transmitters that participated in the process of galvanizing white blood cells toward inflammation sites, and in older studies, it has already been suggested that African peoples had adapted in some way to incessant malaria attacks.



“We conducted this research based upon the hypothesis that adaptation over millennia to protect from infectious diseases in Africa, resulting in more robust immune response, could be related to more aggressive breast cancer in a modern environment. When we compared levels of certain inflammatory markers between women of African and European descent, we noted many differences,” according to Song Yao, the lead author on the study. “After we ruled out the effects of lifestyle factors, we found that much of these differences could be tied to the Duffy antigen receptor, whereby African Americans have a genotype that helps to protect from malaria.”

Ancestry, of course, is something that 23andMe as well as its competitor, Ancestry.Com, market as a service by way of their products, which are DNA testing kits that would effectually show the consumer his or her family tree going as far back as possible. People use these tests for all sorts of reasons, and even though there was once a time when such tests were considered health services and nothing more, they’ve come to signify more than just tests for hereditary diseases that the consumer wants to know about in advance. US regulators have taken actions that stifled that angle to some extent because it was arguably on the verge of privatizing medical history as a concept. Now, the main point of advertisement for these companies is on the ancestry itself.


Family tree, a chart representing family relationships in a tree structure / Photo by kubicka via Shutterstock


“The ancestry service is a collection of features that give you a comprehensive look into your history, from the very ancient past, 60,000 years ago with Neanderthals, up to the recent past,” according to the head of 23andMe’s ancestry program, Robin Smith. In this way, it’s technically not about medical history or heredity per se; however, this presents a problem for 23andMe. The company is now suing its main competitor, Ancestry.Com, for copyright infringement. They want Ancestry.Com to be compelled to change its name, which is a trademark they claim inherently monopolizes their market, but more importantly, they’re suing on the basis of a patent dispute. The patent in question is essentially the analysis of genome loci shared by members of the same family — genome regions they classify as “identical by descent” or IBD.

The lawsuit’s only worthwhile because heredity is the new, hot commodity. In 2017 alone, over 15 million people traced their genealogy, and two million of those did so only within the last quarter of the fiscal year. The entire global population remains, however, which presents nigh-incalculable profits for both companies — twice as incalculable if only one continued. The work their doing is essentially a populist science based on the work that researchers like Song are doing. The findings of the latter, in fact, are demonstrating just how important the findings of the former can really be, and they show that knowing whether someone’s ancestry is European or African can inform a consumer’s understanding of his or her own immune system’s heritable strengths and weaknesses. For a woman with breast cancer, that might prove to be invaluable information if timely.

“These findings indicate that evolutionary adaptation many thousands of years ago shaped our immune systems, and may still have considerable influences on immune function today,” Song adds. “The next research question we are pursuing is whether those evolutionary marks play any significant role in affecting breast cancer health disparities.”



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