MAR 07, 2021 7:14 AM PST

Tuberculosis Influenced the Human Genome

WRITTEN BY: Carmen Leitch

Throughout human history, our species has come into contact with both harmless and infectious microbes that have changed us, like gut bacteria and retroviruses. But more recent infectious disease outbreaks have also left their mark on human biology. New research reported in the American Journal of Human Genetics has suggested that tuberculosis (TB) has had a variety of influences on human biology, including the genome.

A medical illustration of drug-resistant, Mycobacterium tuberculosis bacteria / Credit: CDC/ Antibiotic Resistance Coordination and Strategy Unit / Photo Credit: Medical Illustrators: Alissa Eckert; James Archer

"Present-day humans are the descendants of those who have survived many things: climate changes and big epidemics, including the Black Death, Spanish flu, and tuberculosis," noted senior study author Lluis Quintana-Murci of the Institut Pasteur in France. "This work uses population genetics to dissect how natural selection has acted on our genomes."

In this research, the investigators focused on changes in one gene called TYK2, which has been associated with the function of the immune system. Previous work has indicated that a homozygous variant in that gene called P1104A is linked to an increase in the risk of a serious illness due to Mycobacterium tuberculosis.

By assessing a dataset containing genomic information from 1,000 ancient Europeans, the researchers determined that the P1104A variant emerged over 30,000 years ago. Further study that went beyond genomes suggested that the variant became far less frequent around 2,000 years ago. At about that same time, current forms of pathogenic strains of Mycobacterium tuberculosis became prevalent. The P1104A variant has not been linked to other infectious microbes.

"If you carry two copies of this variant in your genome and you encounter Mycobacterium tuberculosis, you are very likely to become sick," said first study author and graduate student Gaspard Kerner. "During the Bronze Age, this variant was much more frequent, but we saw that it started to be negatively selected at a time that correlated with the start of the tuberculosis epidemic in Europe." People that carried this variant were more likely to get TB and die; the variant was therefore less likely to be passed on to children.

"The beauty of this work is that we're using a population genetics approach to reconstruct the history of an epidemic," Quintana-Murci explained. "We can use these methods to try to understand which immune gene variants have increased the most over the last 10,000 years, indicating that they are the most beneficial, and which have decreased the most, due to negative selection."

The tools used in this work may provide insight into other genetic variants that play a role in other infectious diseases.

Sources: AAAS/Eurekalert! via Cell Press, American Journal of Human Genetics

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
FEB 10, 2021
Genetics & Genomics
The Evolution of Snake Venom From Predation to Protection
FEB 10, 2021
The Evolution of Snake Venom From Predation to Protection
The venom of some spitting snakes has evolved to cause more pain to mammals, a defense mechanism likely meant to fend of ...
FEB 11, 2021
Microbiology
Investigating the Microbial Life of Sourdough, International Bread of Mystery
FEB 11, 2021
Investigating the Microbial Life of Sourdough, International Bread of Mystery
Sourdough bread has a unique taste because it's not made with years from a packet; it's made with wild yeast that gr ...
FEB 28, 2021
Microbiology
Tourists Are Often Exposed to Superbacteria
FEB 28, 2021
Tourists Are Often Exposed to Superbacteria
Researchers and clinicians have long been warning about the rise of antibiotic resistant superbugs, pathogenic bacteria ...
MAR 21, 2021
Genetics & Genomics
Deciphering How Some Environmental Influences Affect Development
MAR 21, 2021
Deciphering How Some Environmental Influences Affect Development
We know that there are certain substances that can harm a developing fetus, like alcohol or lead. Some health conditions ...
APR 08, 2021
Immunology
It's Not Just Cholesterol That Clogs Arteries
APR 08, 2021
It's Not Just Cholesterol That Clogs Arteries
Researchers have discovered a gene that is directly linked to the development of cardiovascular diseases, such as high b ...
APR 05, 2021
Health & Medicine
April is Autism Awareness Month
APR 05, 2021
April is Autism Awareness Month
April is autism awareness month (April 2 was autism awareness day), during which people are encouraged to learn more abo ...
Loading Comments...